The tool-assisted speedruns for Red Ball 4 volumes
1, 2, and 3 are absolutely insane. Released from 2012 to 2013, these three installments share
various glitches and physics exploits that speedrunners have utilized for almost a decade
to beat these games significantly faster than intended. Most notably, a double jump glitch is
used in almost every single level to skip various puzzles and obstacles to attain a much higher top
speed than otherwise possible. However, thanks to the more recent development of tool assisted
speedruns for these games, the true potential of Red Ball 4’s mechanics and its physics engine,
Box2D, have finally been realized. In early 2021, humans were barely able to break the 3 minute
barrier in Red Ball 4 Vol.1 Any% thanks to the discovery of a new glitch in level 15, the Boss
Roll, that saved almost 25 seconds. However, soon after this feat, roblox8192 and Koala
Bread authored a TAS of the game that clocked in at one minute and 59 seconds, an entire minute
faster. For a game this short, the difference was absolutely mindblowing. By programming a seemingly
perfect sequence of inputs ahead of time, the TAS built up a large amount of speed in the
early levels and then maintained it for almost the entire remainder of the run. Double jumping and
corner boosting were far more broken than people could have ever imagined just a few months prior.
After roblox and some others gave Volumes 2 and 3 the same treatment, the minute gap over the Any%
real-time records persisted. Fast-forwarding to the present day, 50 more seconds have collectively
been saved with the current Any% TASses, and it’s almost all thanks to one person, Starline, who is
the primary author of each run. So, please join me as I explain the magic behind the tool-assisted
speedruns of the Red Ball 4 Flash volumes. If you have seen my Red Ball TAS Explained video
released in 2021, then you are probably aware of some of the barriers that exist to making
tool-assisted speedruns of flash games. To make a “proper” TAS of a Flash game, you have
to find an emulator that is able to run it and then hope that your emulator and game combination
is also supported by the Linux TASsing utility libTAS. Back in 2021, the most advanced Flash
game emulator, Ruffle, had zero compatibility whatsoever for games programmed in ActionScript 3,
which included the entire Red Ball series. To TAS these games, the community had to create modified
versions of each installment to provide features like save states, pausing, frame advance, memory
watch, and input recording and playback. For the Red Ball 4 volumes, each of the mods were created
by Face_McDude, an extremely impressive feat given how obfuscated the code is when decompiled. While
Ruffle compatibility has improved enough over the past 2 years to make the Red Ball games somewhat
playable, poor performance and differences from the stock Flash Player has prevented it from
being used in any kind of Red Ball speedruns for the time being. Therefore, every Red Ball
4 TAS, including the three primarily authored by Starline that we will be analyzing,
were created with Face_McDude’s TAS hacks. Typically, the games look like this when playing
back an input string and this with the player details disabled. But for your viewing pleasure, I
further modified the games to improve the heads-up display and add widescreen support. These values
track Red Ball’s x and y position in units, these values track his x and y velocity in units per
second, this tracks his current angle in radians, and this tracks his angular velocity in units per
second. Red Ball’s circumference is approximately 4.19 units, meaning that an angular velocity of
that value would represent a full rotation each second. The y axis in Flash is opposite of the
typical coordinate plane, so negative y velocity points upwards and y position increases as you
go downwards. The stage size is 640x480 pixels no matter how large you make the game window,
and there are 30 stage pixels per unit. In Any%, there is no requirement or restrictions on
glitches or medals and achievements collected, and timing begins the first frame that Red Ball
is visible after skipping the opening cutscene. Just one level in, there is already an enormous
amount to unpack. At low speeds, while Red Ball is on the ground, pressing the right button will
increase Red Ball’s x velocity by about 1.19 units each frame and his angular velocity by 0.567 units
each frame. The physics engine wants these two values to be equal, so it converts some of the x
velocity into angular velocity at a 1:2 ratio….. almost, so the frame ends at 1.07 x velocity and
0.81 angular velocity. The next frame, the left button is pressed in addition to the right button,
which you may think is equivalent to pressing nothing, but that is actually not the case. With
no input on the ground, Red Ball will lose 1.7% of his speed each frame, but when pressing left
+ right at low speeds, this decrease is actually ignored. The exact purpose of this left press
isn’t known because the inputs for level 1 were actually mostly generated with a bruteforcing
script, which tried around 100,000 combinations to determine which one produced the fastest time
with the highest exit velocity. Regardless, this pause allows Red Ball’s x velocity and angular
velocity to roughly equal out at 0.98. From here, it’s not really feasible to go frame by frame to
explain Red Ball’s changes in velocity because the system for doing so is orders of magnitude
more complicated than it is in Red Ball 1. All you really need to know is that the game has a
soft cap of 11 for velocity in the x direction, meaning that the game will stop applying
acceleration from the right button once this value has been reached. However, if this limit is
able to be exceeded, say by rolling down a slope, the game will allow that velocity to be
maintained. At this spot on the slope, we will already witness the first instance of double
jumping in the run, and this is how it works: If the jump key is pressed for exactly 1 frame,
there is a window of 3-8 frames inclusive after this input where pressing jump again will yield
an extra jump. The game uses this formula to determine what y velocity to add to Red Ball when
jumping based on what his y velocity will be on the next frame, before the jump. If it will be
greater than -2, the jump will subtract 9.55 from the y velocity. If it will be less than -5, the
jump will subtract 4.775 from the y velocity. And, if it will be between -2 and -5, the amount
applied follows a linear relationship between -9.55 and -4.775. With a double jump, the
grounded jump always yields -9.55 y velocity, and since gravity adds 0.5 to Red Ball’s y
velocity every frame, the second jump always yields an additional -4.775 y velocity. While a
jump always applies the same upwards force to Red Ball no matter how long the input is pressed, this
6 frame window means that there are 6 different heights that can be obtained from a double
jump. This glitch is an artifact of a mechanic implemented in the game called coyote time, which
allows the player to still jump up to 8 frames, or .267 seconds, after they have fallen off of a
platform. This grace period is intended to make the game feel more “fair” to play and patches up
the issue of jump inputs getting ignored if Red Ball is slightly airborne after getting kicked
up by a small bump on the ground, something which happens quite frequently. The problem
with this system arises because upon jumping, Red Ball will be on the ground for 1 extra frame
before actually becoming airborne. By doing a 1 frame tap, the game applies the jump force to
Red Ball, starts a 3 frame jump cooldown timer, and disables the coyote jump flag, but on the
next frame, before the physics have processed, it notices that Red Ball is on the ground without
the jump key pressed, so it re-enables the coyote jump flag. After the jump cooldown timer expires
on frame 3, Red Ball is able to jump again because it thinks that he just fell off of a platform
due to that one frame of being on the ground without the jump key pressed. Consequently, it
is impossible to perform a double jump after a coyote jump because the flag isn’t reset. Red
Ball exits the ground with 10.4 x velocity, and while airborne, Red Ball does not gain or lose
velocity unless the opposite direction is held, meaning that speed is maintained for this
entire section of the slope. In contrast, simply rolling up the slope causes the
x velocity to drop to as low as 8.63, a decent bit slower. Unlike Red Ball 1, objects in
Red Ball 4 have zero restitution, or bounciness, so Red Ball’s y velocity is immediately set to
zero upon hitting the ground in most situations. As alluded to earlier, the speed
from going down the slope causes Red Ball’s x and angular velocities
to go past 11 into the high 14s, where another frame 6 double jump is performed
to clear these stairs without slowing down. Now, due to imprecision in the mating of
edges, rolling over almost any vertex in this game will cause Red Ball to get either a
vertical or horizontal bump. The direction and magnitude of the bump depend on a multitude
of factors, including the angle between the edges and Red Ball’s position and velocity.
Right before the bridge, there is a spot in the ground that Red Ball normally gets a small
vertical bump from, which slows him down since some x velocity is converted into y velocity.
However, Box2D intentionally incorporates a certain amount of leeway when determining if
two objects are colliding. For Red Ball 4, this tolerance is set to 0.005 units, or 0.15
pixels. While the ground is at y = 5.4583 units, Red Ball lands at y=5.454 units, a height that
he maintains since it is within the range. This is just enough of a gap to allow Red Ball to roll
over the corner without getting a bump from it. Red Ball’s angular velocity increases on the
bridge while his x velocity slightly decreases, but upon landing, the two values equal out at
roughly 15 after the 2:1 conversion. A frame 3 double jump is performed to skip moving
this box. The transition to the next level begins once Red Ball’s center is within 30
pixels of this right boundary wall. Since Red Ball has a radius of 20 pixels, there is
essentially a 10 pixel wide zone that he can land in to end the level without physically
contacting the right wall. Since Red Ball is traveling at 15 units a second, or 15
pixels per frame, landing in this zone is not a given. If Red Ball misses the sweet spot
and contacts the wall on the transition frame, all of his x velocity will be taken away before
being placed in the next level, something that becomes even more of an issue at higher and
higher speeds. However, by planning ahead, the TAS can ensure that speed is always maintained
between levels, even if it means losing a few frames from intentionally nonoptimal movement
through the level. The TAS performs a jump on the transition frame, the force of which will be
applied on the next frame, the start of level 2. When the game loads in level 2, the 3 frame
jump cooldown timer that was initiated at the end of level 1 is reset, meaning that Red Ball is
instantly ready for another jump. Red Ball’s spawn position for level 2 is slightly in the ground,
so a coyote jump can go through on frame 1. This technique is known as a screen double jump, and
since it isn’t bound by the typical 3-8 frame window, it allows for access to a wider selection
of double jump heights. The amount of speed going into level 2 was perfectly planned so that the
frame 1 screen double jump would position Red Ball for an optimal corner boost off the back of
this platform. The apparent speed boost comes from a good chunk of y velocity being converted
into x velocity, and it often allows for a double jump to be performed afterwards, as it is
here. Red Ball converts some angular velocity to x velocity on this box and then performs a coyote
jump to land on the next platform sooner. A single jump sets up a nice boost and horizontal bump
off of this slope, whereafter, a frame 3 double jump sends Red Ball to the end of the level,
where another screen double jump is initiated. The screen double jump perfectly sends Red Ball to
this slope where he is able to build up even more speed. Left is tapped for a frame, which decreases
angular velocity by about 0.567 at high speeds, leading to an effective decrease of 0.19 x
velocity. This leads to a better slope boost later in the level. Red Ball perfectly skims off of the
boulder after a frame 8 double jump, incorporating another left tap and converting just enough x
velocity into y velocity to clear the wall and land on top of the slope. Thanks to those two left
taps, Red Ball will conserve speed into level 4, and he is set up for an insane boost on the top of
this second slope. A huge velocity conversion and a horizontal vertex bump combine to get Red Ball
from 21.3 to 23.3 x velocity. This boost is the reason why, despite there being several ways
to beat level 1 a frame faster than it is in this TAS, it is ultimately not worth it to do so.
The possible speed generated from the slope just isn’t as significant. These kinds of tradeoffs
are persistent throughout many levels in the TAS, as precise speed manipulation through left
taps and neutral frames is often necessary to allow things to work out 1, 2, or more
levels down the line. A frame 4 double jump is performed on the wooden platform to make
Red Ball carry -7.83 y velocity into level 4. The screen triple jump allows Red Ball to clear
the entire starting gap, completely avoiding the cart that you are supposed to roll back
and jump on to cross it. Red Ball gets a tiny boost by landing on the intersection between
these two edges, yielding him just the right amount of speed for him to conserve it into
the next level. A frame 7 double jump is used to clear this entire bridge section and set up
a corner boost on the end of the ground here, getting Red Ball up to 24.7 x velocity. A coyote
jump is performed after rolling off of the box to just barely clear this entire valley, fully
bypassing the boulder and box push puzzle. A frame 3 double jump is performed just before the end to
set up another screen triple jump into level 5. The third jump is executed as a coyote jump on
frame 8, which completely skips the slope and positions Red Ball to get a boost off the back
of the boulder. Left is pressed alongside jump to reduce his angular velocity by 0.567, which
ultimately saves time due to allowing for a more optimal level 6 completion. A frame 6 double
jump places Red Ball on this rolling cart, and two normal jumps carry him
to the end with -0.55 y velocity. This value was carefully manipulated to
make Red Ball get out of the ground quicker at the start of the next level, causing less x
velocity to get converted into angular velocity.
A left tap is performed on frame 1 to
slightly reduce Red Ball’s angular velocity, which sets up a perfect corner clip on this
wooden spoke after the jump, converting a huge amount of x velocity into y velocity. A frame
2 coyote jump is performed, and a one frame left shift is used to make Red Ball land at this
spot, perfectly clearing the elevator. Since Red Ball is still moving upwards, his y velocity is
not reset upon making contact with the ground, so a jump here is able to increase it to -11.51.
A frame 5 double jump allows him to barely avoid the cart that you are supposed to ride to solve
a short puzzle to clear the wall at the end of the level. Red Ball gets a small vertical vertex
bump at this spot on the slope while initiating a frame 6 double jump to land on the front corner of
the ending platform, yielding a horizontal vertex bump. Left is tapped the frame before finishing
the level to allow for a more optimal level 7. Level 7 is actually one of the few levels in
the game where Red Ball spawns slightly off of the ground, which makes it impossible to set
up a screen double jump or triple jump. Still, at 25.72 x velocity, Red Ball is easily able
to cross over the starting gap in a single jump. Thanks to precise position and velocity
control, Red Ball is poised to enter the 0.15 pixel leeway zone above the ground on the next
frame rather than fully contacting it. Alongside a left tap before the frame 6 double jump,
these minute changes in position and velocity lead to a slightly better corner boost on this
wooden spoke. With an immense 26.37 x velocity, a single jump is all it takes to cross this
entire water-filled gap. Left is pressed for two frames to reduce angular velocity to set
up a better cart bump in level 8. Additionally a screen triple jump is set up
before entering the next level. A 1 frame left tap and a frame 5 coyote jump set
up a corner boost on the platform all the way over here. A left press upon landing and a
jump here perfectly sets up a double jump off of the corner of the cart the same
frame the jump cooldown timer expires. This effectively yields a triple jump, which
generates enough height to clear the windmill. An unavoidable vertical vertex bump is garnered
after Red Ball rolls off of the starting ledge. A frame 6 coyote jump carries him to the top
spoke of this turbine that you are supposed to spin to raise this slope to make the jump
across the gap possible. A left tap followed by a frame 5 coyote jump allows Red Ball to
clear the wall with just about 0.6 pixels to spare. A single jump is all that is needed
to cross the pond, and a coyote jump off of the slope effectively gets him to over 27 x
velocity. After jumping off of the wood platform, Red Ball barely grazes the corner of the ending
platform to reset the coyote jump flag while expending a negligible amount of x velocity.
By jumping at -2.9 y velocity, Red Ball ends the level with -9.8 y velocity, which is exactly
what is needed for a perfect entry into level 10. By entering the level with a large magnitude of y velocity instead
of garnering it from a jump in level 10, Red Ball can land on this box a single frame
sooner. It’s worth mentioning that it is possible to get way more speed off of the ending slope in
level 9, but doing so causes you to overshoot this box if you don’t slow down. A frame 8 double
jump combined with a left shift for later barely gets Red Ball to the top spoke of this
turbine while it is slanted upward, converting some angular velocity into x velocity. The left
shift comes into play, as a frame 7 double jump yields a good boost from killing this enemy. The
bounce sets Red Ball’s y velocity to -8, which is enough to reach the ending ledge. A jump is
performed on the transition frame into level 11. The transition jump lands Red Ball on the
top of this box, and some angular velocity is converted to x velocity as a result. This
slight conversion happens due to the box moving slightly right when Red Ball touches it. It
is possible to get a boost off of the box’s top right corner by jumping a frame later and
pressing left, but it ends up not being worth it. A last frame coyote jump gets Red Ball to the
next box, but this time, velocity converts in the opposite direction. A normal jump gets him to
the top of the ramp, where a vertical bump is garnered on the first vertex. In this instance,
it is quite beneficial, as it allows Red Ball to just barely land on the back of this loop and get
a boost. A coyote jump carries him to level 12. Level 12 is the first level where the game’s
“puzzle fail” mechanic becomes a concern. For most levels, it is possible to put them in a
state where it is no longer possible to clear them through conventional gameplay. If you
push a box or a boulder into a spot where it cannot be recovered from, odds are, the game has
a trigger to detect that and will reset you to the last checkpoint automatically. However, level 12
is unique in the fact that the game will count a puzzle failure if you decide to avoid the boulder
entirely. This makes sense because you can’t get back up this slope with a single jump, and you
aren’t supposed to be able to get over the right wall without the boulder. While Red Ball is within
this region of the level, the game will check for two conditions each frame: whether the boulder is
past the top of the slope, and whether the boulder has an x velocity of greater than 0.25. If either
of these conditions are met, the game will not count a puzzle failure, since it indicates that
the boulder will either make it down the slope or has already made it down. The entire beginning of
the level is meticulously set up for Red Ball to get just enough of a push on the boulder while
losing as little speed as possible. There is a one frame left shift after the coyote jump, and
the ground is landed on with only the jump key pressed. This causes Red Ball’s angular velocity
to be reduced by 5% on the next frame. Because of some jankiness with how this pseudo-friction
system is implemented, the 5% reduction happens again on the next frame even though Red Ball is in
the air. The purpose of reducing angular velocity here is so that the boulder will receive less of
a leftward force from Red Ball’s rotation while receiving the same rightward force from his linear
momentum, leading to a greater net push to the right. Another double jump is performed off of the
boulder with some angular velocity manipulation, and Red Ball soars to the end of the level.
However, for the first time, a considerable amount of speed is expended on purpose… you’ll see why
in a moment. A screen triple jump is set up going into level 13. Ultimately, Red Ball entered level
12 with 26.07 x velocity and left with 16.64. After all that precise speed reduction and
a screen triple jump, Red Ball clears this obstacle at the start of level 13 with probably
a bit more room than you’d expect from a TAS this precise. However, the tiny bit of extra speed loss
is necessary to position Red Ball on this tilting platform in a spot where a double jump will allow
him to clear this armored enemy. That’s what we were actually setting up for. A frame 4 double
jump sets up a corner boosted double jump on the front corner of the pond, and Red Ball exits
the level with an effective 19.403 x velocity. Since Red Ball spawns off of the ground
in this level, it's not possible to set up a screen triple jump. With a frame 3 double
jump, Red Ball barely makes it onto the cart without bonking. There is a 1 frame left tap
on the slope, and after launching off of it, Red Ball lands perfectly for a corner boost
off of this platform and this boulder. A frame 7 coyote jump is performed to make Red Ball
land on this plank a bit later, delaying the angular to x velocity conversion. This is done
to manipulate Red Ball’s x position so that, after the double jump to clear the wall, he
gets a more optimal corner boost. A coyote jump is performed to avoid this enemy, and
Red Ball makes his way over to the boss fight. However, before we get into the TAS completion,
it’s necessary to see how things are supposed to go down. The fight is split up into three distinct
phases that each require the player to do very different things. In phase 1, the boss starts
by rolling to the left side of the screen in aggro mode, meaning that any contact will damage
the player and reverse his direction. However, if the boss crosses the 3.33 unit mark on the left
side of the level or the 18 unit mark on the right side, he becomes vulnerable for up to two seconds.
If Red Ball hits the boss in his vulnerable state, he will take 1 heart of damage, and a 16 frame
cooldown will start where Red Ball cannot damage or be damaged by any enemies, including the boss.
The boss’s damaged state also lasts for 2 seconds, so despite the cooldown, you can consecutively
hit the boss as many times as you want, resetting the cooldown and damaged timers each
time. However, you won’t deal any extra hearts of damage by doing this. After hitting the boss
3 times, phase 2 will initiate, where the boss ground pounds to drop a normal enemy from the sky,
which Red Ball must kill to make the boss roll to the other side and initiate the next wave. Next
come 2 normal enemies, and then 2 armored enemies, which each require 2 hits to kill. After
expending those guys, phase 3 initiates, where the boss bounces either 4 or 5 times on
the ground before becoming vulnerable. After 3 more hits, the boss loses his last heart, and
the fight is over, taking a total of around a minute to complete with no glitches. So,
let’s now see how the TAS takes on the boss. A sub-21 second fight. Red Ball hugs the left wall at
the start of the battle, and a few frames after the boss becomes vulnerable, the right
button is held. After damaging the boss, Red Ball remains in contact for a good chunk of
the 16 frame cooldown timer, hoisting him to the right. This makes the distance that the boss needs
to travel to the next vulnerability zone shorter. While you can hit the boss back to the left in
his aggro state to get another hit in much sooner, this can only be done twice throughout the
whole fight, since Red Ball dies after taking a third hit. It’s faster to budget those hearts
for later. Red Ball charges to the right and jumps over the boss, hitting left upon contacting
the wall while continuing to spin to the right. He deals a hit the same frame the boss becomes
vulnerable, and because of the rightward spin, the boss slides on top of Red Ball. That’s
when this incredible maneuver comes into play. Once the boss crosses the 3.33 unit plane,
he becomes vulnerable for another hit, which is taken after the boss bounces off of
the wall. Now that the boss is at 3 hearts, the game is waiting for him to become aggro again
to initiate phase 2 of the fight. However, the TAS doesn’t allow for this to happen, as the boss is
launched back to the right side of the screen in the refreshed damaged state with the help of that
16 frame cooldown timer. Since phase 1 behavior is still active, the boss again becomes vulnerable
after crossing the 18 unit plane, and a fourth heart of damage is dealt on the first possible
frame. This all is simply a faster version of the Boss Roll glitch that was shown at the start
of the video. Since the boss is now at 2 hearts, phase 2 will never start because it is checking
for the boss to be at 3 hearts. The hearts that were budgeted finally come into play, as the boss’
direction is reversed on the first possible frame, causing him to instantly become vulnerable
again, and another hit is dealt the frame the cooldown timer expires. Two seconds
later, this is repeated, and the boss is finished off. Red Ball 4 Vol.1 complete in
1 minute, 39 seconds, and 200 milliseconds. And that’s the Tool-assisted speedrun world
record for this game fully explained. Starline did end up improving this thing by 9 frames
during the creation of this video, but due to factors like the box in level 10 and the platform
at the start of level 13, it is very unlikely for the time to ever go much lower than it currently
is, barring a grand discovery that has yet to be made. In a glitchy physics sandbox that makes
very little effort to take away your speed, the possibilities that are opened up are
quite amazing. And indeed, the impact that Red Ball 4 TASsing has had on the game’s real-time
speedrunning scene has been absolutely monumental. These TAS tools have allowed various frame perfect
setups to be created for the beginning levels and ending levels that allow speed to be built up and
maintained in a way never seen before in RTA runs. A 1-5 setup made by Starline requiring just a few
frame perfect double jumps is what allowed the first sub 2:50 to happen, and a frame-based 12-14
setup is what allowed for the first sub 2:40 to happen. Further developments and persistence from
speedrunners has brought the time down even lower, and a certain speedrunner is currently attempting
a 40 frame perfect input setup that would yield a final time faster than the original sub 2
TAS. But all of that is a story for another day. Additionally, I’m afraid that the TAS
explanations for Red ball 4 Volumes 2 and 3 are going to have to wait for part 2 of this
series. If you thought this TAS was crazy, those 2 are equally as insane, so subscribe if
you don’t want to miss out on it. See you then!
