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Tool-assisted game movies
When human skills are just not enough

Submission #4916: Dashjump's GBA Sonic Advance 2 "Knuckles" in 20:32.08

Console: Game Boy Advance
Game name: Sonic Advance 2
Game version: USA
ROM filename: 0906 - Sonic Advance 2 (U)(Independent).gba
Branch: Knuckles
Emulator: VBA-rr v23.5 svn421
Movie length: 20:32.08
FrameCount: 73589
Re-record count: 73655
Author's real name: Jax C.
Author's nickname: Dashjump
Submitter: Dashjump
Submitted at: 2015-11-24 09:50:28
Text last edited at: 2015-12-03 08:07:14
Text last edited by: fsvgm777
Download: Download (6370 bytes)
Status: published
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ALERTS POSSIBLY COMPROMISING MOVIE INTEGRITY:

Movie begins from a reset; should begin from power-on.

Author's comments and explanations:
Verification movie here (taken from Mukki's run), as this run begins with Knuckles already unlocked.


(Link to video)

I started getting into TASing Knuckles in Sonic Advance 2 sometime in early 2012. I began with TASing random levels to get a feel of the game's physics, while comparing my run times to those on The Sonic Center. When I first worked on this run, most of my individual level timings were just a second or two away from the real-time records. This prompted me to contact Mukki (author of the amazing currently published Sonic run) and ComboBlaze (the current Sonic Advance 2 champion on TSC) for tips, which they willingly provided (thanks a lot!). I've re-done this whole TAS at least 3 times, and have uploaded two of my previous attempts to YouTube, but I'm only submitting this run, which will be my final revision.

Knuckles is quite an interesting character to TAS. Unlike Sonic, he doesn't have airdash, which limits his speed considerably. His signature moves, gliding and climbing up walls (which require cancelling boost mode), are almost useless in this game, as he is almost always better off running and jumping while in boost mode. Nevertheless, Knuckles has instant-stop capability from nearly anywhere (thanks to his glide and his Down+B attack), allowing him to do ninja-like spindash spamming (which I show off in some boss levels) and also allowing him to use a stop-spindash to defeat bosses quickly.

Game objectives

  • Emulator used: VBA-rr v23.5 svn421
  • Aims for a no-emeralds game completion with Knuckles
  • Aims for fastest in-game time over real time
  • Takes damage to save time

The in-game times of individual stages are as follows:

Stage Time TSC record
Leaf Forest 1 0:32.32 0:34.43
Leaf Forest 2 0:28.77 0:29.07
Egg Hammer Tank II 0:05.62 0:05.62
Hot Crater 1 0:38.85 0:42.42
Hot Crater 2 0:39.53 0:42.75
Egg Bomber Tank 0:06.52 0:12.60
Music Plant 1 0:42.52 0:51.78
Music Plant 2 0:51.97 0:56.77
Egg Totem 0:05.50 0:08.58
Ice Paradise 1 0:51.92 0:59.27
Ice Paradise 2 0:42.87 0:46.07
Aero Egg 0:05.57 0:05.90
Sky Canyon 1 0:46.47 0:53.03
Sky Canyon 2 0:47.08 0:52.53
Egg Saucer 0:08.83 0:24.37
Techno Base 1 1:11.45 1:23.88
Techno Base 2 0:42.22 0:45.22
Egg-Go-Round 0:07.48 0:08.77
Egg Utopia 1 1:05.58 1:16.70
Egg Utopia 2 1:09.65 1:19.48
Egg Frog 0:09.30 0:10.38
XX Zone 0:48.47 1:41.92

Knuckles' notable moves

  • Spin dash: it only takes 1 rev (or 2 frames) to perform a full speed spin dash. I use this move a lot when not in boost mode, and occasionally, in boost mode (therefore cancelling boost mode) to gain immediate horizontal momentum. I also rely on the spin dash a lot in the side-scrolling boss stages, because it is the only way to gain horizontal distance quickly in such stages.

  • Glide: By pressing A in the middle of a jump, Knuckles starts gliding forward at a very low speed, and gradually gains speed as the glide continues. This is generally useless for gaining speed as Knuckles would be better off running normally in boost mode, but it is very useful for coming to an immediate stop.

  • Climb: By gliding into a wall, Knuckles can start climbing it slowly. I only use this move once in Techno Base 2 to save time.

  • Punch: Pressing B when not in boost mode lets Knuckles launch a punch forward, damaging enemies. I only use this move once in the final boss of XX Zone, not to do damage, but to gain immediate forward momentum.

  • Corkscrew spin: Pressing B while running in boost mode activates a drill-like attack forward which damages enemies and loses a considerable amount of speed. I do not use this move at all in the run, as rolling into enemies is usually faster.

  • Downward spin: Pressing B in mid air makes Knuckles slowly spin toward the ground, losing all horizontal speed. This would be completely useless if not for a minor bug - where pressing B very near ground will skip the entire animation, making Knuckles come to a stop immediately. This allows for immediate spindashes, and its utility has been described above in the first point.

  • Mid air tricks:
    • Left/Right + R: Knuckles is thrown in the direction pressed at a certain speed and starts rolling after landing, slowing him down and giving him no control over a subsequent jump. However, using this move close enough to a platform skips the animation and prevents Knuckles from rolling, making this move quite useful at times.
    • R only: This is almost equivalent to Sonic's side-spin trick, which gives better control after landing.
    • Down + R: Same as downward spin listed above.
    • Up + R : Knuckles does an uppercut which gives him some air, but he cannot gain any horizontal distance until he starts falling. This is useful on certain occasions for gaining some vertical distance.

Level notes:

Leaf Forest 1

I've redone this stage at least 5 times. This level looks quite straightforward, but the 2nd water section is pretty tricky. I'm not entirely sure if this is a bug, but I found out that rolling at a certain frame completely negates the water friction, allowing me to travel through it quickly.

Leaf Forest 2

Thanks to the level's layout, having no walls protuding from the ceiling, it's possible to gain enough height then glide all the way to the end of the level.

Egg Hammer Tank II

An easy boss to TAS. 5.62 is the absolute perfect timing so there's no more room for improvement.

Hot Crater 1

The jump around the 3-second mark from the slope, under the ceiling and onto the rail should be impossible in real-time, requiring just the perfect velocity, a frame-perfect jump, and holding left for a few frames to land perfectly on the rail.

Hot Crater 2

My previous run used a different route at the beginning, dropping into a pit with a loop to get boost mode earlier. I found out that this was slower than my current route by about 20 frames.

Egg Bomber Tank

Theoretically (according to Mukki anyway), it's possible to achieve a perfect 6.50 timing by landing the last hit on the cannon on the same frame as the first hit on the body. However I couldn't find a position to attack this way, hence my timing was 1 frame slower than 6.50.

Music Plant 1

I believe this is the only stage where the camera actually doesn't catch up for a considerable amount of time. Nothing else noteworthy here except the last two rail jumps are both frame perfect and hence practically impossible in real time.

Music Plant 2

I tried jumping over the spikes seen here in Mukki's TAS, but was less than a pixel away from clearing them without getting hit. This forced me into the lower route for the 2nd half of the level. I also added in a delay before scrolling away the title card, to manipulate the spike cycle at the 45-second mark.

Egg Totem

Sonic and Knuckles are probably the only characters who can achieve the perfect 5.50 timing on this boss, thanks to Knuckles' instant stop capability.

Ice Paradise 1

The jump at the 37-second mark is crazy, requiring a certain velocity which can only be attained from the jump immediately preceding it. I had to cut my speed to align myself on the correct subpixel positioning to get the required X-velocity (which has a value of around 3700). I also get the speed shoes here, as it's required for keeping boost mode after the subsequent Up+R trick and the final jump onto the rail.

Ice Paradise 2

The green shield capsule at the very beginning of the level is a small annoyance; it took some time for me to figure out the precise positioning to get a stop-spindash without hitting the capsule.

Aero Egg

I've tried nearly every single jump interval and positioning, but was unable to get the perfect 5.50. I'm compelled to say that 5.57 is the perfect timing for Knuckles, but I'd love to be proven wrong here.

Sky Canyon 1

It might seem weird to stop, spindash and lose boost mode after the first two dash rings and the rail, but it's actually faster; because maneuvering around the subsequent spinning windmill thingy just to keep boost mode takes up far too much time.

Sky Canyon 2

I sacrifice about 3 seconds of real time at the beginning of the level, in order to manipulate the first moving block to be at its lowest point when I pass through it (hence saving in-level time).

Egg Saucer

The half-pixel syndrome strikes here again. I tried very hard to get in two hits on the very first jump, but missed the positioning by mere subpixels. In the end I only managed to save 2 frames from my previous run (which had a timing of 8.87 seconds).

Techno Base 1

The longest level in terms of in-game time. I use the stop-spindash trick a few times to - even though it doesn't look like it - save some time.

Techno Base 2

Grabbing the random ring capsule is initially slower, but I found out that the frame I which I would collect the capsule happened to give me 50 rings. Rings improve jumping distance, hence this ended up saving time ultimately.

Egg-Go-Round

The four platforms don't materialise until the timer reaches 2.15 seconds. This was a really tough boss to optimise, and I still think the timing can go lower with better positioning.

Egg Utopia 1

Thanks to the diagonal sliding platforms force-removing boost mode, I go through a long section in this level without boost mode. Getting an optimal timing here requires manipulating 3 moving object cycles (the moving spike-ball at 15 seconds, the moving block at 52 seconds, and the spikes at 1:00), which required far too much effort for minimal time savings.

Egg Utopia 2

I had to slow down to grab the random ring capsule (around the 15-second mark) at a certain frame for 50 rings. This is important later on, as I need at least 100 rings to get boost mode from running off the slope at the 46-second mark.

Egg Frog

The hardest boss to TAS. I can't spindash while on the top level, making it impossible to gain any forward momentum there. Getting the proper positioning to defeat this boss quickly was a huge challenge overall.

XX Zone

Amazingly, and thanks to a few positioning tricks I found, I managed to complete XX Zone faster than the current published TASes using Sonic. The positioning here is really weird; contrary to what I believed, your position doesn't reset to a default subpixel after defeating each boss. This proved to be a challenge in the Aero Egg and final boss sections, as very precise positioning is needed to land on the edge of the Aero Egg platform, and to land the first hit on the final boss, respectively.

Special thanks to:

  • Mukki - for giving me precious tips on TASing this game, as well as a lua script which aided greatly in optimisation. This run wouldn't be nearly half as good as it is without his help. Thank you!

  • ComboBlaze (Combo on TSC) - for planning some routes and giving me ideas here and there to improve the run. Thanks!

  • You, for watching my run, and if you read all of this (:


ars4326: Judging!

ars4326: Hello, Dashjump. First off, nice to see that you made multiple passes through this one, before submitting. The technical quality indeed shows! It was also notable how you were able to emphasize use out of Knuckles' "ninja spin-dashing" (both stages and boss fights). Overall, very nice work, and congrats on your first published run :)

Accepting for publication, as a separate branch ("Knuckles"), to Moons!

fsvgm777: Processing.


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