Let's stick to the theme of glitches only found in the Japanese release of games! We'll be looking at Super Mario Bros. 3 today.
What if you could get a level card and an item at the same time?
Level 5-1 allows you to spawn a treasure chest similar to those you find at the end of Hammer Bro. battles. These sprites (and pretty much all sprites) are incompatible with the text that appears at the end of each level, so triggering both at the same time results in a bunch of glitchy graphics appearing.
In the international release of the game, the level was just rearranged so that it was impossible to trigger the glitch in the first place.
Work RAM address $0566 holds what is called the current "level event", which is just a flag for certain sprites or generators to be active. These are:
- No event
- Generate Jumping Cheep Cheeps
- Generate Swimming Spiked Cheep Cheeps
- Force Lakitu to fly away
- Generate Flying Parabeetles
- Background clouds (after beating a Koopaling)
- Generate wooden platforms
- Spawn treasure box when all enemies defeated
- Cancel all level events
We're interested in level event 7, which is the treasure box event. This is used for Hammer Bro., Boomerang Bro., and Fire Bro. battles, but also various other rooms in the game. For example, the Hand levels in world 8, the Piranha Plant levels in world 7, and other hidden bonus rooms, such as the one in level 5-1.
Defeat the bros, and you get a treasure. Why does it always spawn on the opposite side of the screen though?
When the game has detected that there are no longer any sprites loaded in the level, it will spawn a treasure box, and collecting it will end the level. If there are no sprites at the moment the level event is activated, it will spawn one right away. This is how the hidden bonus rooms work. Normally, level event 7 is never activated outside of these bro battles and bonus rooms. But, there is one case where you can.
Level 5-1 has a bonus room you can find at the start of the level by flying up to a lonely warp pipe. This sublevel has a pipe that leads back to the main level, but it also has a skinny path that leads to a dead end room that will trigger level event 7, spawning a treasure box in the room. Collecting it will end the level, but you could also theoretically back out after the treasure box spawns and go back to the main level. Unfortunately the level event resets upon going through a pipe.
I presume the tunnel was made small specifically so you couldn't go backwards after triggering level event 7.
However, the fun thing is that this sublevel is actually the same sublevel as the ending of the level. This is one of those levels that has a pipe at the end of the main room that leads to a short room with just the level end card roulette. If you fly up to the top of the ledge on the left on this room, you can go back and visit the room with the treasure box, just all the way up above the screen.
You can hear the treasure box appear once you fly up here.
By visiting this area, you trigger level event 7 and the treasure box spawns since there are no other sprites loaded over here. Then you can go back to the level end card and you'll be greeted with a glitched out Nipper plant.
If only the Nipper actually turned into a 5-up and a whistle...
Super Mario Bros. 3 will dynamically swap in the proper graphics tilesets for the currently loaded enemies. However, if two enemies are incompatible--that is, they share graphics in roughly the same area of the memory mapped CHR ROM--they can't be loaded at the same time, so one of them will glitch out. In this case, the treasure box makes the Nipper show incorrectly.
When you hit the end level card roulette, it causes all sprites on screen to turn into coins. This includes the Nipper if you haven't killed it, as well as the treasure box (since it persists even off screen). This will cause a second treasure box to appear after you touch the roulette card. If the box appears on the left side, nothing else interesting happens.
You got a card! But you left the treasure box behind. :c
However, if you make sure the screen scrolls as far as you can to the right, and you kill the Nipper so a coin doesn't appear from it, and you touch the left side of the roulette card, you can get the treasure box to appear on the right side of the screen. This causes Mario to collect it as he exits stage left.
This will make the music box appear. Normally, special graphics are loaded that contain the "Course Clear!" text. However, the music box forces the normal in-level graphics to persist, so when these tiles are drawn, they show up as various in-level tiles instead of the text.
The existence of the music box forces the graphics with the course clear text to get overwritten.
If this end level card is your third in a matching set, Mario will not collect the treasure box, but its graphics are still incompatible with specifically the single digit in the "xUP" sprite that appears, causing it to glitch out as well. Actually, this also happens in a mixed card set if the treasure box appears on the left side of the screen too.
I like how it's only the number that glitches out, but "UP" is still just fine.
Here is what the loaded CHR ROM banks look like at the end of the level:
The intended graphics are on the left, while the glitched graphics are on the right.
In order to fix this in the international release, the ending of the level with the roulette card was just placed at the end of the main level room, eliminating the pipe transition altogether.
There used to be a Buster Beetle here too, but he got deleted too, rip.
Interestingly, the bonus room still has a copy of the end of the level in it, so you can actually clip out of there after triggering level event 7. Too bad the roulette card is missing!
I used a P-Wing to get out of the treasure box area, but that makes it a lot harder to clip out of this room.
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