Chaotix needed some love! So I'm trying to complete it.

Introducing, Chaotix Complete!

Chaotix was never finished: this is common knowledge (I think it is, at least). Chaotix also receives so few rom hacks: there are what, five of them, excluding this one? And 2 or 3 of those are just sprite or palette mods. We can do better!

The goals:

1. My main goal? To answer the question, what if Sega actually finished the game they intended to build, rather than rushing it to the 32X in an incomplete state?
2. The end game should be fun, especially for coop play. I think Chaotix has the best potential for cooperative play from all the classic games, thanks to the tethering.
3. I’ve got a lot of thoughts on what a completed Chaotix game would be, and I’m not the only one who's asked that same question. I’ve been sorting through old Sega documents, art, other people’s ideas (pretty much anything I can find) for a year, despite only starting on this project in early 2026.
4. Aside from finishing a fun game, I want to make tools that people can use.
5. I want to document this game as much as possible.

What is this?

This version is pretty much just some bug fixes, and “What if Chaotix shipped with Sonic and Tails?”. I think the community deserves to play that game.

Bug Fixes:

1. Fixed (kind of) physics. You can roll down slopes now. It doesn’t feel like characters randomly accelerate with no reason now. What a nightmare. Every now and then I’ll be playing this updated version and think I broke something, and then I’ll go back and realize it’s in the base version too.
2. Spin dash: One of the reasons I believe people who say “This game was made by the Sonic CD team” is because of how murked up the spindash was. Between the sound driver side not pitching up the sfx, and the physics side not accelerating, the spindash has been fixed.
3. Sonic’s legs have been re-colored in the good ending.
4. Heavy’s throw animation has been restored, and he has a couple new sprites to account for him actually holding the other player. Offsets were also added for the walking + hold animation. Let me know if I missed any sprites with him
5. Level select: you can choose from any of the base characters. Heavy and bomb are fully playable as P1/P2 for masochists out there.
6. SFX:
7. Rolling never had a sound effect. That’s been fixed.
8. Some general sound driver fixes

New Features

1. Sonic and Tails are fully implemented. They have their S3K moves—after all, that’s the precursor to this game. Sonic also has the drop dash, in addition to elemental shields.When Sonic has no shield, or has a neutral shield, he can use the insta-shield (jump, short press jump) or drop dash (jump, long press jump).
2. Normal shields give sonic a larger insta-shield! If you feel like that’s OP, please let me know. Everyone in this game feels OP to me, so I find that balance to be fair since he has no vertical traversal abilities.
3. When Sonic has elemental shields (more on that below), they behave the same as S3K.
4. Tails can fly for 8 seconds. Jump, and press/hold Up to fly. This is how he behaved in the beta. Jumping from the ground while holding Up gives tails a super-jump-fly thingy. This wasn’t intentional, but it does add to the balance of his gameplay and I’m keeping it since Charmy is OP in this game and this helps Tails balance with him a bit.
5. Tails does not have his tail overlays while jumping in the bonus/special stages yet.
6. Elemental shields have been ported from S3K. Win them in the bonus stage for now.
7. I’m still porting elemental damage types over, as Chaotix does not that baked into attacks/enemies.
8. Speaking of the bonus stage… the lightning shield attracts rings in the bonus stage if you have it (not the special stage yet). HUD icons also appear for what shield your player has in the bonus stage, since I haven’t gotten overlays working yet.
9. Every character is selectable from the player select screen. If you want to beat this game as Heavy, why should I stop you?
10. Oh, that little flippy-monitor animation now plays with more items, not just the blue ring.
11. I suppose the added splash screen counts as a new feature?

New Art

1. Many sprites were provided by @CancerEdition. Some were from other games. Some are new!
2. The HUD icons for Knuckles and Espio look good on CRTs due to the way the pixels blend together. They look bad on any other display, so I’ve fixed that and made new sprites.
3. HUD icons (while we’re on them) did not have borders for characters. This inconsistency has been fixed.
4. Knuckles didn’t used to slide on the ground when he landed. Now he does, and there’s new art for that. I guess that’s also a new feature?
5. I made some new art for the instashield when Sonic has a shield power up. I never finished that, but the placeholder works for now.

New Sounds

1. A restored Sega sound. Since this sound is still in the game, and the sound went through at least two iterations, I’m guessing it was turned off for development purposes. Believe me, booting this game up hundreds, or thousands of times, would make me shut off that sound too.
2. Imported Sounds from S3K, and from Sonic CD.
3. FM/PSG jump SFX (this is in the options menu)
4. Jump SFX also change pitch when you’re big/little. Isn’t that cute?
5. Skid SFX alternate between PSG and FM, dependent on the option. I’m really wondering why the skid SFX were PSG in this game, when the jump was FM—especially since Chaotix relies so heavily on the SCD sound bank. Find that toggle in the options menu.
6. FM/PSG saves to SRAM, so when you reboot the game, it remembers what you chose.

Known Bugs

Sorry everyone, I've run out of time for a few months to work on this, and wasn't able to finish mapping the overlay positions for Sonic and Tails.

1. Sonic and Tails' arms are incomplete.
2. Tails' tail overlays are incomplete.
3. It's still Chaotix.

There’s a lot that I’ve fixed in this game. I don’t remember all of it right now. So this list is not exhaustive. Like I said, September was nuts. I’ve got builds with water, builds where Heavy’s sprites are kind of restored, a build with smooth sprite rotation working. I haven’t had time to review the code on those and implement it into the main build of this project.

I’ve got a lot of plans for this hack in the future.

Enjoy v0.1 of Chaotix Complete, AKA the Sonic and Tails in Chaotix build.

— Adam Kempenich