Sonic the Hedgehog (16-bit)/Bugs

General bugs

Missing Press Start Button text on title screen

The text “PRESS START BUTTON” was meant to be displayed on the title screen. However, due to RAM not being properly cleared after the two previous screens, it does not appear. The byte that should call for it to appear is shared with the previous screens, and since the RAM in this area is not reset, the value is stuck in a no call state. For a more technical explanation, see the Sonic Retro forums

here. To fix this bug and thereby display the text in-game, see this guide.

Not fixed in any version

Hidden points bug

When collecting the hidden points above the signpost at the end of the level, the game only rewards 10 points for the 100 point flags. A explanation how to fix the bug on your own is available here.

Not fixed in any version

Missing percussion after 1-Up music

After collecting an extra life, if you pause the game as the main zone music starts to fade in, when you resume the game, the music resumes fading in but without percussion. Percussion is restored for the next music track that is played (completing level, getting invincibility monitor, getting extra life, etc.). This also affects the Special Stage theme, but in a different way: FM channel 6 is disabled because the Special Stage theme uses 6 FM channels, unlike every other song in the game. In this case, the game need not be paused for the glitch to occur; it occurs after the song fades back in.

Not fixed in any version. It is however interesting to note that this cannot be reproduced in Sonic Mega Collection. This is due to an inaccuracy in the emulator, and not any fix to the game itself.

Time counter doesn’t flash

If the player is in the ninth minute, but he has at least one ring, the TIME counter won’t flash red because of a mistake in the HUD code.

Not fixed in any version

Continuous Invincibility Music

If the player has invincibility, and obtains a life at exactly the right moment as the invincibility music is about to end, the life jingle will interrupt the music transition, and afterwards, the invincibility music -minus the stars around Sonic- will continue to play until the player dies, enters the boss area or collects another invincibility box. This is extremely hard to do, and has to be timed perfectly. A video of the after effects can be seen

here - (second post down, second video).

Not fixed in any version

Spike damage bug(?)

When normally attacked, you gain a brief moment of invincibility to get your rings back or destroy the badnik that hit you. However, the spike routines don't check to see if this is true, so if you get hit on a row of spikes, lost your rings, and bounce back onto it, you lose a life straight away. This applies also to shields; so, if you have rings and a shield, the spikes will take your shield, rings, and life one bounce right after another.

To fix this in a disassembly, see this page.

Note that there has been some debate over whether this behaviour was an intentional feature, but a majority of people classify it as a bug. No official confirmation has been made either way, but the bug was fixed in Revision 02 of Sonic the Hedgehog, a.k.a. the version in Sonic Mega Collection. And, of course, Sonic 2 and subsequent main-series games altered the behaviour to match all other forms of damage.

Level bugs

See the External Links below for a video about these bugs

Zip through walls in Scrap Brain Zone

On the first act, find the ledges that move right then left. Go to the far right side of the wall and wait for the platform to move to the right. As soon as it starts to move right, duck. You’ll go through the wall. While here, press to zip right and to zip to the left.

Fixed in Sonic the Hedgehog Genesis

Speed Tunnel Scrolling in Green Hill Zone

On the first act there is a series of two speed tunnels with a star post in the middle. Occasionally, if Sonic is moving too fast the screen won’t scroll down fast enough, and when Sonic touches the bottom of the screen he will die, as if it were a pit.

Fixed in Sonic the Hedgehog Genesis

Crash game in Labyrinth Zone

At the end of the first two acts, if the camera is panned down at the moment the results screen is about to appear, the game may crash with an Illegal Instruction exception. The SCHG has a fix for this bug.

Fixed in Sonic Classic Collection

Go through solid marble in Marble Zone

In Marble Zone, during the sections in which Sonic rides a square rock through lava and there are square walls blocking the way, the player can crouch and go right through the marble walls instead of having to jump over them.

Fall off level in Final Zone

It is possible to fall off the edge of the level after defeating Eggman. This is only possible if Eggman is hit one final time when trying to escape. If not, Sonic’s forward movement will be stopped when jumping near the edge.

Fixed in Sonic the Hedgehog Genesis

Final Zone Boss bug

In Final Zone, getting the final hit on Robotnik early in the round will allow a player to hit him again while the piston slowly retracts. This action loops his hit counter from 0 to 255, and interrupts the defeat sequence, making Robotnik restart his attack pattern. The only thing that can be done at this point is to fight on until Time Over or allow yourself to be killed and restart the stage.

Fixed in Sonic the Hedgehog Genesis

Going too high in Star Light Zone

On the first act there is a place with an Orbinaut. Jumping there is OK, but if you’re pushed higher, by getting hit, you’ll die.

Fixed in Sonic the Hedgehog Genesis

Missing sign post in Labyrinth Zone

At the end of Labyrinth Zone act 2, if you head towards the signpost and stop near the area where the camera locks and walk left, the signpost object will be deleted and will not be reloaded. Afterwards, if you enter the signpost area, the camera will lock and you will be stuck until time runs out. If you have over 50 rings the big bonus ring will appear in the area you're stuck in. If you jump into it, Sonic will disappear but you will still be stuck on the level screen. If you wait for the time to run out, you will hear Sonic's dying sound and the time will stop at 9:59, but you'll be stuck on the level forever. The only thing you can do is reset or turn off the game. A video of this bug can be seen

here.

Player bugs

Jumping next to solid objects

In certain circumstances, but most often when next to a solid object, jumping will use the wrong animation, so that Sonic appears to walk in mid-air. This happens often in Marble Zone whilst on the blocks that float on the lava. This also happens in Green Hill Zone Act 2, at the second block (the one with the yellow spring on top). If you want to fix the " walk in mid-air " bug go here.