Sonic the Hedgehog 2 (16-bit)/Bugs

From Sonic Retro

Revision as of 21:47, 15 March 2009 by Nineko (talk | contribs) (Music tempo change: it's -> its)

Player bugs

Super Sonic at the end of a level

The Super Sonic glitch in action
Attempting to transform into Super Sonic after hitting a signpost or prison capsule results in Sonic "walking" in mid air, and becoming unresponsive to controls. If Sonic moves off the right side of the screen before this happens the score tally will appear and the game continues on to the the next level as normal. If he does not leave the screen he will get stuck with no way of ending the level. The player can't wait for a time over, because passing a signpost stops the timer. The only thing to do in this situation is to reset the game.

Note: Prison capsules make the score tally appear automatically, so the level will always end.

Fixed in: Final revision 02

Tails high score

If Tails hits an enemy after Sonic has just died, he gets stuck and gains a large score (as well as several extra lives). [1]

This bug occurs in all known betas and prototypes; an easy way to reproduce it in the Wai beta is to go to Hidden Palace Zone, immediately Spin Dash to the right, and press jump as Sonic dies.

In the final, Tails starts flying when Sonic dies, making him unable to hit enemies.

Fixed in: Final version

Life counter glitch

If a player dies from time-over in a 2P Versus mode while on their last life, the Game Over routine will be interrupted and the results screen will be displayed. The player who died will appear to have 0 lives, but if they die again, the counter will roll back to "y5" (255), as the lives are stored as an unsigned byte, and the life counter was only meant to display up to 99 lives.

Not fixed in any version

Multiple Badniks in a row in 2-Player mode

The shared combo counter glitch in action
It's quite common knowledge that if you destroy several badniks in a row you're awarded more and more points. However, this behaviour is present also in Sonic 2's 2-Player mode, and the counter of destroyed badniks is shared between the players. Example: If Sonic destroys a badnik, and Tails quickly destroys another badnik, Tails will get 200 points, and vice-versa. First noticed
Sonic Retro

Not fixed in any version

Level bugs

Emerald Hill Zone scrolling

In Emerald Hill Zone, the bottom two rows of foreground pixels don't scroll horizontally, causing them to be permanently misaligned.

Not fixed in any version of plain Sonic 2; Fixed in Knuckles in Sonic 2.

Hill Top Zone Rexon crash

On Hill Top Zone, it is possible to crash the game when hitting Rexon (the snake-like badnik that sits in the lava). Conflicts in the code cause it to jump to a section of code it was never meant to jump to. This results in invalid opcodes being processed and an eventual crash.


Oil Ocean Zone physics

In Oil Ocean Zone act 2, find the area with four green platforms which launch into the air occasionally. Step on the last one and when being shot out of the the tube hold right and land on the spikes in a way that will knock you into the round object to the left. If done correctly the physics will be different and the character will jump higher. The bug eventually wears off when getting in another speed tube, jumping on a spring, or passing through a wall. Alternately you can use this Pro Action Replay code while on that level FFB82C:04. This code only works when reaching that area.

Not fixed in any version

Miscellaneous bugs

14 continues chime

When the 14 continues cheat is performed by playing sounds 01, 01, 02, and 04 on the options menu, an invalid sound attempts to play, resulting in non-stop Oil Ocean music for the remainder of the game. The fault is with the way the sound number is entered into the game's code. For every sound, the bit 7 must be enabled to properly reference it. The code instead is written without bit 7 being used.


Music tempo change

If the 1up jingle is playing while the super sneakers wear off, the level music will not revert back to its normal tempo.