Hey! Thank you!
I think context is important here. This is a Game Boy Color game.
There's nothing I can do about the jittering for browser. It's a limitation of GBC and emulation. It doesn't jitter at all on my Anbernic, but will on my PC.
With old consoles, they have a horizontal draw limitation for sprites. Certain emulators can remove this. But only 10 sprites can be displayed per scanline. That's why sprites will disappear. each character is 2 sprites wide 16x16 (two 8x16 sprites).
the continue thing is a bug. I'm updating it now.