Water, water everywhere...

I was thinking wishy-washy thoughts, and my attention came to water. I thought, "How does water work in Sonic 2?" So I did some research and came to a small snippet of code consisting of two BEQ commands, two CMPI commands, a BNE command and a MOVE command. This was the method by which the game decided whether or not to load water for a specific level. Then I thought "How do I change which levels load water?" More research revealed a complicated process which was difficult. So I thought "Surely you can just change the various commands - BEQ, CMPI, BEQ, CMPI, BNE, MOVE - for a single BRA command? That would always load water, surely?"

So am I right? If not, why not?

 

Uh-oh, double-post time.

I've made a hack which basically changed the last Break if Not Equal (BNE) command to point to the same thing as the previous Break if EQual (BEQ) commands. The result: Water, water everywhere, and glitches to make us think. I'll put up a link to my little hack and let you lot do the testing. I've already tested EHZ1 a little, and found two glitches:

• If you manage to get to the top of the screen, the graphics which would ordinarily be the waves on the surface show up as bits of Buzzer.
• The knob-like things at the ends of bridges kill you underwater. I have no idea why though.

Here's the hacked ROM.

 

So it was. It;s fixed now though.

 

I tried to follow the guide at SHacNet, and it kinda... didn't work. Unless my "start water here" figure was wrong. I'll copy the water height for CPZ2 or ARZ and make it work, but the SHacNet guide is too patchy and involves too much "oops, forgot this". They could simply tell you how to do it without saying "put bb- oh no, put eeee".

Nonetheless, thanks very much.

 

I used 68kd. Nemesis knows where it can be found, and he's posted numerous times on the subject in a topic on assembly code in the Sonic Cult forums.

 

Yeah, they kill me too. Don't bother with that ROM anymore though. Just a small exercise in pointlessness, and a good bit of fun too.