Hide your shame

Reader muteKi pointed out something interesting over at my post on level sizes. By default, Carnival Night Zone 2 has an unusually low ceiling:

;                       xstart  xend    ystart  yend    ; Level
                dc.w    $0,     $6000,  $580,   $1000   ; CNZ2

The reason for the lower ceiling is to keep you from going back up the shaft and reaching the innards of the act 1 boss scroll, which are replicated in the act 2 layout for some reason. This would be trivial to do by say, climbing up the shaft walls as Knuckles.

However, something was still bugging me. I was sure you could go up there somehow. So I checked my disassembly of standalone Sonic 3, and sure enough, what do you know:

;                       xstart  xend    ystart  yend    ; Level
                dc.w    $0,     $6000,  $0,     $1000   ; CNZ2

The ceiling is completely unlocked in standalone Sonic 3. The addition of Knuckles as a playable character is likely the reason why this was changed. Even so, if you select Sonic and Tails, use the act 1 signpost to reveal the thunder barrier monitor hidden in the floor, then have Tails carry Sonic up as high as possible, and finally use the barrier to do a double jump, you can just barely get the camera outside the shaft. It's not enough to get Sonic up there, though.

While investigating this, I noticed the level size for Launch Base Zone 2 is also different between games. Here's what it looks like in Sonic & Knuckles:

;                       xstart  xend    ystart  yend    ; Level
                dc.w    $0,     $6000,  $0,     $B20    ; LBZ2

And here's what it looks like in Sonic 3:

;                       xstart  xend    ystart  yend    ; Level
                dc.w    $0,     $6000,  $0,     $1000   ; LBZ2

In Sonic 3, the level's pants are down, so if you go all the way to the bottom, you can see where the background plane ends and also get a good look at the level's sewers. This was fixed in Sonic & Knuckles due to Knuckles' route through the stage making this pretty evident.

It's not really an issue in Sonic 3 because Sonic and Tails never go low enough to actually see it. Once again, the level size was changed due to the addition of Knuckles as playable character.