[vidarh]

32/64 colours, assuming no rewriting, but given the very existence of the copper was motivated by being able to change values like that, plenty of Amiga games exceeded that. Some very substantially.

The copper was also used to multiplex sprites, so again the limitation is per scanline.

And assuming things wouldn't be changed per scanline is assuming a shoddy job - very few games on the Amiga would not make at least some use of the copper to extend the number of sprites or number of colours on screen.

[lttlrck]

I have very vague memories from the time when Lemmimgs was released, something about the sprite/copper that allowed it to display those Lemmings efficiently. Of course the Atari ST had the exactly same game which puzzled me, though presumably it used brute force.

[vidarh]

I think it's more likely it "just" had more colours, and possibly used a different graphics mode for parts of the screen. Lemmings strikes me as a game where the size and number both precludes using sprites for all of them, and where moving the Lemmings themselves shouldn't be computationally costly enough to be a problem.

Though the Amiga does allow changing the positioning of the screen over a larger bitmap, so e.g. panning the levels without much/any copying might have been an option? Doesn't require the copper, though.