So I've been grinding on 8-1 and learning the various pipe lip jumps throughout the level. I noticed some odd behavior with how the goomba despawn strategy works and I'm kinda baffled if it's due to sprites on screen and/or framerule.

Essentially after doing the second pipe lip jump I noticed that the set of three koopa's doesn't always spawn three (sometimes two). Regardless of two or three being spawned, if you don't kill the first one in that set it will not despawn a goomba in the next section. Killing the first koopa always seems to despawn it. Any ideas as to why it's only spawning two koopas, and the issue with killing the first one to despawn a goomba? As a caveat I also noticde that if two koopas were spawned the plant in the pipe is also spawned whereas when three are spawned it isn't.

Below is a clip of where only two koopa's were spawned for reference. Any ideas?

Those despawn are due to the game having a large number of sprites on screen. I believe the max sprites that the game can load on-screen is 6 (I may be wrong). Since killing that koopa despawns the goomba because when you kill the koopa it's shell stays on-screen, so since the game doesn't want to get to get overloaded by all the sprites, it removes one of the goombas. I don't know why the third koopa despawns though. I'd assume it's because you didn't kill any goombas so the third goomba before the koopas was on-screen longer. But I'm not too sure. 🤔

I should have said hit the koopa, not kill it. It's pretty odd that sometimes it spawns two koopas versus three. It's interesting to me.

When you were doing pipe jumps, I noticed you tapped left, just to make sure to not die to the Piranha Plant, that's the reason why 3rd koopa despawned. I guess because you slowed down, some of the enemies are appearing later, some earlier and the sprite limit is changing which enemy to despawn because of that little difference in timing.

Ahh thats probably it, sprites on screen appearing later definitely makes sense. It's insane because that left tap is so quick as is.