Sonic CD Quirks

@Clownacy I went ahead and reposted the ring sound bug and sound priority bug explanations on my Sonic CD Deconstructed account, and provided additional examples to help explain them. I should note that the "stop all sounds" command is played every time it exits an MMD file, not just when leaving the time warp cutscene.



As an addendum, they also forgot to assign sound effect 0xDF (drowning) a priority value.

 

3D ramp/loop

I made a video about how a 3D ramp/loop works in Palmtree Panic Act 1 Present:


Additional notes:

• Gravity is only disabled if Sonic is going fast enough (at least 8 upwards). If he slows down, then gravity is enabled, which is why when you let go of the jump button, he starts falling.
• He will also only be boosted forwards if he's moving fast enough.

Metal Sonic projector sprite cropping

The Metal Sonic projector's sprites have the 1st row of pixels cropped out in the 1996 PC version:


This actually extends to the 2011 remake a little, where a couple sprites have that cropping issue, but others are just fine:

 

Explosions and flowers are flipped depending on the direction of the badnik in the original version of Sonic CD.



This is because the way the explosion and flower are spawned are by sequentially changing their object ID and resetting their routine ID back to the initialization one. However, during re-initialization, it fails to reset the flip flags, and that's why it does that.





Usually, using OR to combine bits with previously set ones are used by stage objects placed in the stage layout to retain settings set by the layout data. They probably just copied that line without much thought into the explosion and flower objects.

This does not happen in the 2011 remake.

 

Here are some videos of the final boss with hitboxes visible in the original Sega CD version and the RSDK version; the hitboxes are quite different.

 

There are some invisible blocks placed in Metallic Madness.


They don't exist in the 2011 remake.