Different enemies ? so our trusty circle will be demoted to background enemies where more pressing enemies force the user to remove the threat.
Not really. There will only be one type of enemy per level as mixing them up Echoes or GW style would mean you couldn't really employ any tactics other than survival. With a single enemy type you can exploit it's behavior to help in colouring the background....possibly.
I'd advise though, in a game like Mono where the late game becomes so important not to add an enemy which seeks the player, that just annoys me to no end.
Well the enemies in the current version of mono home in on the player so I say you're wrong in this case
In fact if you know how the background colours effect the gamplay then you'll also know that "homing" is an integral part of the gameplay.
Ah touchez, i'd forgotten about that. Oh I much prefer the one enemy type per level system, should allow us to focus on colouring the screen.