Huh. The EU/US release date of Sonic 2 was "Sonic 2s day", on the 24th, but the JP one was the 21st. Today's the 21st, and a Tuesday... Er, anyway, Sonic 2 is very buggy. Looking at the massive bugfix thread should be a good indication. That thread also seems to indicate that some people want a hack that tries to fix as many of these bugs as possible. Well, this is that. Broken Chemical Plant Zone door? Broken multisprite mirroring in 2-player? Inconsistent 'E's in the title screen? Tails's macho-man arms? What else? Spoiler Fixed a huge number of issues in the sound driver (check FixDriverBugs in the Git disasm for more info) Fixed demo playback not emulating held buttons Fixed Nemesis decompression race condition crash Fixed Sonic being able to turn Super after touching the signpost and softlocking the game Fixed Sonic being able to turn Super after opening the animal capsule, and hanging in the air Fixed Super Sonic being abnormally fast after transforming underwater Fixed Super form ring drain speed so it's *actually* one ring per second Fixed Super Sonic roll deceleration speed so it's not unnatural Fixed Super Sonic's transformation being glitchy when you've already transformed once in the level before Fixed Super Sonic transformation palette fade so the last colour isn't skipped Fixed Super Sonic transformation palette fade being incorrect when underwater Fixed Tails' roll deceleration speed so it works like S2 Sonic instead of S1 Sonic Fixed roll-jumping using Sonic's regular collision hitbox Fixed the player's jump height being nerfed when jumping out of shallow water Fixed spin dashing when at the level boundary Fixed spin dash losing its speed if you jump immediately after releasing Fixed numerous drowning bugs Fixed camera jittering up and down when rolling while playing as Tails Fixed Tails' tails bugging out when he's stood next to a solid object Fixed Tails' tails so they flash too when he gets hurt Fixed Tails respawning with the wrong speeds if he died underwater Fixed rings accidentally deleting in levels that wrap vertically Fixed scattered rings so their despawn isn't delayed if you quickly lose rings again Fixed monitors so you don't pass through them when jumping at them from the side Fixed EHZ scrolling bug at the bottom of the screen Fixed CPZ boss goo not hurting Sonic if he ducks Fixed ARZ boss pillar so you can't fall through it by jumping on it Fixed ARZ boss arrows, so you don't hover by walking off one of them Fixed ARZ boss pillars so you don't hover if you're stood on one when the boss is defeated Fixed ARZ boss animations freezing when it hurts the player Fixed a bunch of strange CNZ boss behaviours when you first hit it Fixed HTZ background so part of it doesn't jitter when scrolling Fixed OOZ launchers making Sonic fast if he falls into one after getting hurt Fixed final boss's collision, so you don't get sucked into it and die if you hit it a certain way Fixed MTZ/HTZ/ARZ bosses so their parts don't fall off in the wrong direction when you beat them Fixed multiple bugs involving Sonic/Tails using the wrong speeds Fixed Tails not getting a smaller hitbox when he ducks Fixed Sonic/Tails glitching out if they fall into a CPZ pipe by being hurt Fixed AI Tails using the wrong sprite when flying because he hit a forced-roll object, the EHZ spiral, or the MTZ cylinder Fixed the camera warp trick seen in speedruns Fixed the second player's background being wrong in two-player CNZ Fixed MTZ's wall springs/MCZ's vines locking Sonic/Tails' controls when you roll-jump into them Fixed Silver Sonic/ARZ/OOZ/MTZ boss strange behaviour when you beat them on a certain frame Fixed MCZ boss writing to a random part of the Mega Drive's memory Fixed the horizontal level wrap trick seen in speedruns Fixed MCZ boss not laughing when he hurts Sonic/Tails and they drop rings Fixed bridges interfering with Sonic in debug mode Fixed various instances of the game clearing too much memory Fixed object collision from below Removed duplicate WFZ PLC entries Fixed sprite table overflow (Ashura glitch) Fixed ARZ waterfall corrupted graphics #Fixed strange notes in CNZ credits music Fixed CNZ act 2 background blank row Fixed DEZ/CPZ door sprite so they're not corrupted Fixed debug mode having an inconsistent camera Y-deadzone Fixed ARZ pillar objects disappearing while on the edge of the screen Fixed getting a Game Over in HTZ corrupting the Continue screen Fixed ARZ/MCZ/DEZ boss rumbling causing the background to distort Fixed HTZ bridge stakes objects disappearing while on the edge of the screen Fixed starting the game through the options menu not reseting the number of collected Chaos Emeralds Fixed Sonic keeping his invincibility stars when he goes Super Fixed multi-sprite objects not mirroring in 2-player Fixed drowning next to a monitor causing Sonic to die in his walking animation Fixed Tails' pushing animation oddities Fixed DEZ music not resuming after beating Silver Sonic Fixed objects like the MCZ crushing pillar being able to make Sonic enter his walking animation while charging a spin dash Combined REV02's bugfixes with REV00's missing features. - Fixed game crash that happens when you enter debug mode while dying and place an object - Invisible wall object is now visible in debug mode - Invisible MTZ wall bumper object is now visible in debug mode - Fixed crash that occasionally happens when you kill a Rexon Fixed errors in Sonic's mappings (one walking frame, and the black-and-white frame of his transformation) Fixed the player being able to walk around during the tally after touching the signpost by jumping near the right side of the screen Improved boot time Removed duplicate/inaccessible rings and objects Fixed Sonic's hand disappearing for one frame on the title screen Fixed a certain wall in CPZ2 that you could walk through by jumping over a plane switcher object Sped up level loading Fixed HTZ solidity so it's not possible to fall so fast that you clip through the floor and die in that one tall lava room in act 2 Restored un-clipped Snare, Kick, Timpani, and Sega samples from Sonic 1 Made drums fade with the rest of the music, instead of immediately going silent Fixed inconsistent 'E's on the 'THE HEDGEHOG' part of the title screen Fixed Super Sonic transformation not taking Sonic out of ball-mode (roll-jump control lock, smaller hitbox) Fixed ARZ having too many blocks, causing it to overflow its RAM buffer Fixed Sonic/Tails not slowing down, or creating a splash, if they fall into water after getting hit Fixed Level Select icons showing the wrong palette briefly right after changing the selected zone Added an invisible block to prevent a certain falling pillar from pushing you through the level in ARZ1 Added an invisible block to prevent that platforms on the lava at the start of MTZ2 from pulling you through the ground Fixed frame-perfect Sonic/Tails sprite corruption and other minor irregularities in WFZ/ending cutscenes Fixed 14-Continues cheat causing OOZ music to play for the rest of the game Fixed "erratic" behaviour with object's detecting their distance from walls to their left Fixed 2P animated art loader accidentally overwriting its own loop counter Fixed rings disappearing when near the top of the screen Fixed rings not shaking with everything else during things like the HTZ earthquake sequences Fixed Tails having flesh-coloured arms in the Special Stages Fixed the shoe on the Speed Shoes monitor not having a white stripe on it Fixed HTZ seesaws not cancelling the spin dash if you're launched while charging it Fixed shield poking through the bottom of the tunnels in EHZ/HTZ (Check out 'credits.txt' for a list of guides I used, by the way.) Because I want to avoid some issues I've seen in similar hacks, this actually comes in two builds: a 'Pure' one that aims to be just vanilla Sonic 2 with as many fixes as possible (a theoretical REV03, basically), and an 'Impure' one, that has some non-bug-fixing design choices like Super Sonic detransformation and S&K style "slow ducking": Spoiler Made it so you can duck while moving at slight speed, similar to S&K (though unlike S&K this does not change how fast you have to be to roll) Removed air speed cap Added S3K-style Super transformation, except you have to use alternating buttons, and you can detransform Made Tails able to enter Debug Mode Download here.