Tired of always helping Sonic get by, Tails has finally decided it is his turn to break the game. This run goes where no other runs have gone before and uses a disassembly of the game in order to squeeze the most of every trick.
Emulator used: Gens 11b + S3KCamhack + SolidityViewer + (partial)HitboxDisplay + LUA HUD for Genesis Sonic games
Commentary with HDL and Marzo (sadly, lacking video due to technical issues)

Game objectives

  • Ignores delays caused by bonus effects
  • Aims for fastest (primarily in-game) time
  • Takes Damage to save time
  • Abuses death
  • Abuses programming errors
  • Counts time spent dying
  • Manipulates luck

Comments

New tricks

"Stair" clip

When a character is on-air, not moving upwards (i.e., vertical speed is zero or it is downwards), and his vertical speed speed is at least equal to his horizontal speed (in magnitude), he may fall through otherwise-solid ground. If the pixel portion of the vertical velocity plus 8 is greater than the distance both of the character's bottom collision anchors are inside the floor, then no collision with the floor is registered and the character can fall through. This is explicitly used in HCZ1 to enter the wall, and at LZR (both acts) to clip through the stairs. It is implicitly used to speed up entering the ground in LBZ1 and in MHZ1.
I believe this extra check was added to let you fall through a higher ledge when jumping to it from below if you did not go high enough to reach it.

Camera locking

In general, bosses wait for the camera to lock before they do anything. In all such bosses, the camera position was manipulated to make it lock as soon as possible.

General Comments

This run was made with constant reference to the disassembly available at Sonic Retro. This disassembly was used to determine the exact positions where the camera locks, how bosses and badniks behave, how several glitches work, and so forth. All this information is being collected and revised, and will be released in the future.

In-Game Time Table

ActTime[1]
Angel Island 10:40::48
Angel Island 21:15::32
Hydrocity 10:20::47
Hydrocity 20:24::35
Marble Garden 10:35::30
Marble Garden 20:31::08
Carnival Night 10:36::20
Carnival Night 20:31::31
IceCap 10:48::44
IceCap 20:00::42
Launch Base 10:33::17
Launch Base 21:06::35
Mushroom Hill 10:34::20
Mushroom Hill 20:47::30
Flying Battery 11:01::14
Flying Battery 21:06::31
Sandopolis 11:09::43
Sandopolis 21:11::33
Lava Reef 10:51::50
Lava Reef 20:21::55
Hidden Palace0:26::44
Sky Sanctuary0:53::28
Death Egg 11:04::51
Death Egg 21:44::31
Total18:49::29

Time lost to deaths

ActTime[1]
Hydrocity 20:05::19
Death Egg 20:04::31
[1] The value after the final colon pair indicates the in-game frame counter, and is restricted to the 0-59 range. It is updated every frame (except during lag frames), and increments the in-game second when resetting to zero.

Level-by-Levels comments

Here we mostly only mention what's not obviously clear when watching the run, each other situation pretty much speaks for itself or has been used in earlier TASes of this game.

Angel Island 2

By jumping at the right spot by the entrance to the tunnels, you don't slow down and thus save a considerable amount of time. With Tails, taking the upper route was the faster option.

Hydrocity 1

Here we abused a variation of the stair clip, which in this case was much harder to execute as the object that stops the horizontal movement resides quite far from the edge of the terrain. A small bit of time was lost to setup the quick death at the start of the next act.

Marble Garden 1

Tails can't sink far enough when jumping from the rolling state and therefore can't enter the yellow spring like Sonic, and thus a slightly longer route was necessary. There was luck manipulation at the end of the level: we caused a few extra signpost sparkles to be created to manipulate the MGZ2 boss pattern.

Marble Garden 2

There is a glitch that affects the boss fight: when the character is in a certain range of positions, the game will trigger the screen shaking and rising terrain. The problem is that going over the top of the screen when far enough to the right will trigger this. The main issue is that this creates a lot of terrain that make it impossible to break through the roof of the boss' arena. For this reason, the glitch is triggered early, so that this additional terrain has moved up enough to let Tails go in. There is a bonus to this glitch: while on air, Tails is dragged up by 3 pixels every 8 frames, meaning he can deliver 7 hits while above the screen.

Carnival Night 1

Wheel glitch happens because of the wheel's very large "hitbox", which encompasses the monitors, coupled with a bug in the code that short-circuits the case when the character is standing on an object. We could not jump for the boss fight or we would lose wheel glitch (which we want to keep for the next act), so the fight had to go a little slower than it could otherwise be done.

Carnival Night 2

Jumping off the barrel does not end wheel glitch. Wheel glitch is used along with a bug in the game's collision checking to enter the wall; after that, comes an ultra-rare vertical zip. We then used the glitched gravity to fall horizontally all the way to the boss.

IceCap

When only having one character, the slope glitch can still be activated by standing on the very right part of the moving ice-block as you hit the wall. Running though the act is faster then rolling as your speed won't be capped when you reach 16/pixels frame.

Launch Base 1

Here we abused the spike crusher to quickly perform a level wrap.

Launch Base 2

This was the most resilient level by far -- we simply found no way to break it with Tails. Due to a stroke of luck, we did not have to luck-manipulate the flamethrowers out of the way. At the first boss we flew over an invisible wall in order to start damaging the boss earlier.

Mushroom Hill 1

The boss' flames were on the way, so they were manipulated away at the start of the level with pauses.

Mushroom Hill 2

The upper route is the fastest, so we took the upper route. Tails is the only character other than Hyper Sonic that can gain enough speed to jump all the way to the bottom route at the end without help.

Flying Battery 1

A zip exist in the early part of the act, but that proved to be ~10 frames slower than the method that is used here instead. However zips became useful after the outdoor area to get to boss much faster.

Flying Battery 2

As the boss in the previous act is defeated, standing on the edges of the capsule will give you the slope glitch, which is used here to speed up the act considerably. The rising terrain at the end is triggered by camera position, not character position. Also, once triggered, there is nothing that can be done to speed up their rise. Once the terrain stops rising, it is replaced by a platform object which allows jumping through.

Sandopolis 1

Jump out of the sand, up the sand fall, fly to the platform above, hit the ceiling to zip left to a level wrap, wait for the boss to get close to the quick sand, hit it once - done. Luck manipulation at the end of the level: we caused a few extra signpost sparkles to be created to manipulate the starting positions of the SOZ2 ghosts.

Sandopolis 2

The ghost manipulation before the start of the act made it possible to play the whole act with the lights out. A number of glitches were used throughout the act including screen wrap, falling through the floor, the stair clip and spin dashing through a sprite off screen.

Lava Reef 1

Here we entered Knuckles starting area to perform a level wrap using the spike crusher. The hand boss was manipulated to be in the exact spot we want it to be by adding pauses at the start of the level.

Lava Reef 2

Level wrapped through most the act and then used the stair clip to pass the objects blocking the pipe.

Sky Sanctuary

The boss can move in different patterns and needs to be manipulated at the start of the act.

Death Egg 1

In the beginning we abused the extending stairs to perform a small zip.

Death Egg 2

Used another stair to enter the wall and work our way to a level wrap.

Other comments

Thanks goes to Nitsuja and Upthorn for their Sonic runs; to Orkal for his glitch videos; to HHS for his explanation of the Angel Island/Hydrocity transition glitches; to mike89 for his blooper videos; to HDL for hosting the TAS, and for his general awesomeness at this game; to the folks at SonicRetro involved in the making of the S3&K disassembly.
The Launch Base 1 crusher trick was found by DMTM with Hyper Tails; DMTM also discovered the Death Egg 1 zip.
S3KGlitches found out the Lava Reef 1 level wrap with Knuckles; we soon put it to use with Tails.
gamble5688 found out the DEZ2 level wrap, and he discovered that the LBZ1 platforms pulls you through walls.

turska: Judging.

turska: Great audience response. Accepting for publication to Moons as a new branch.

TASVideoAgent
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EDIT: Stream done. Watch the highlights of it at http://www.twitch.tv/ihdl/profile
feos wrote:
Only Aglar can improve this now.
marzojr
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Just to be clear, the stream is today, October 4. Edit: it is live now. Edit 2: Stream now over.
Marzo Junior
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Watched on stream and must say I'm impressed, lot of new tricks and crazy stuff I was not expecting. Yes votin
WST
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Obvious yes vote, not much else to say. I only want to ask: what is the purpose of those pauses in the end of MGZ1, when the flag is falling? read in the comments, thanks
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THC98
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I watched that on the stream and other time in the emulator. I loved everything I saw, great work! YES VOTE!
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http://www.twitch.tv/ihdl/b/467329664 Skip to 5:00. The audio and video are desynced, but beggars can't be choosers. Anyway, about the run itself, ALL of the yes. As a casual runner of S3K, I can only say :O EDIT: I expect an explanation of Hydrocity 1 and its RTA viability. Explained afterward in the VOD.
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Tails is all, "Ima do this so I can get back to science"
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Watched the archive.org link Great TAS. Every time you think you're going to get bored of horizontal underflow and zips the TAS ramps in how much complexity it has to go through to beat the level. The S&K part in particular is really great. Yes vote.
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Post subject: Tails Lava Reef Act 1
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I had to add some info about this great TAS! Years back I met S3kglitches on youtube. I showed him the crusher zip with hyper sonic. Then he starting to think around it. =D With other words. S3kglitches and I found the crusher zip in Lava Reef Zone Act 1. Nice work both of you guys!, YES VOTE!!!!
I'm not a speed runner, but a game lurker, that's my contribution to the scene. =)
ars4326
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Lol, did I just see a subliminal image of Tails @2:19 on the stream link?
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I love watching speedruns and TASes of the 2D sonic game with a sub optional character because each character is different and interesting as it is. But to be able to abuse specific errors with that character makes it a lot of fun to watch. I give this a yes for sure!
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ars4326 wrote:
Lol, did I just see a subliminal image of Tails @2:19 on the stream link?
No, just the Tails Doll.
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LancexExWx wrote:
I love watching speedruns and TASes of the 2D sonic game with a sub optional character because each character is different and interesting as it is. But to be able to abuse specific errors with that character makes it a lot of fun to watch. I give this a yes for sure!
I would not strictly call Tails a suboptimal character. There are many levels in which Sonic cannot beat Tails’s time. His ability to fly often allows for shorter trajectories and time-saving glitches.
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Impressive! I like how one of the bosses at the end of Launch Base still keeps moving around during the end level tally :)
WST
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WST wrote:
New tricks … "Stair" clip
Is it really that new? A lot of TASers abuse it, and also it was used in previous published runs of this game.
This run was made with constant reference to the disassembly available at Sonic Retro. This disassembly was used to determine the exact positions where the camera locks, how bosses and badniks behave, how several glitches work, and so forth. All this information is being collected and revised, and will be released in the future.
Would be nice if you put those information to the game resource page on TASvideos wiki
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WST wrote:
Would be nice if you put those information to the game resource page on TASvideos wiki
I don't really see the point in duplicating information that's already available on Sonic Retro, but a link to their resources wouldn't be unreasonable.
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Derakon wrote:
I don't really see the point in duplicating information that's already available on Sonic Retro, but a link to their resources wouldn't be unreasonable.
The information in question is on code form (68k assembly); I have been figuring it out and describing it in a more accessible form.
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Ahh, my mistake. Thanks for the correction.
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Jungon
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I now see proof that Tails can fly without spinning his tails =P Yes vote all the way \o\
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Finally Tails gets some love! Some nice new tricks and a few golden oldies, my jaw was stuck to the floor for most of the run- definitely Tails' finest half hour and definitely a yes from me.
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Oh man. A Tails TAS! Finally! I'm so happy I caught this early. What a great tas. So many tricks I havnt seen before. Deff yes from me. <3
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Interesting thing I noticed: the D-pad input is being registered for player 1 and 2 at the same time. In other words, the input box on Gens shows the D-pad directions as white, instead of blue. Some extra entertainment could be used when running from the bombs in AIZ2... Other than that, the run was pretty great! It was entertaining, seemed optimized, and it showed just how diverse Tails can be from the other two characters, while still showing what an S3&K TAS is all about.
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WST
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Espyo wrote:
seemed optimized
Lol, beleive me, it’s optimized to absolutely unhealthy level :) By the way,
marzojr wrote:
By jumping at the right spot by the entrance to the tunnels, you don't slow down and thus save a considerable amount of time. With Tails, taking the upper route was the faster option.
Is this trick really new? I had abused it in one of mine and Qwerty’s very early Amy@S3K WIPs. You may clearly see how I added it between WIP-2 and WIP-3. (upd) did not notice that it’s not listed in «new tricks» section. Nevermind :)
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Espyo wrote:
Some extra entertainment could be used when running from the bombs in AIZ2...
It's faster to just continue to run here, as the speed from the spindash before the bomb section is stored even though you appear to be running much slower. If you slow down you'll only go to the boss area at regular running speed (or you can spindash at the right time, which is still slower than storing it from earlier since rolling causes you to decelerate on flat ground).