Hey, first of all let me say that I love this mod. The idea is just great. I decided to run a map with no enemy bases to fully experience the breamness.

One thing that I would consider a bug, though, is that you can start getting medium biters and spitters as low as 5% evolution, when they would normally only come at 20% and 40% respectively. A quick and dirty fix to this could be to just add an extra "small" at the start of your size arrays, to push back the medium biters a bit.

(I fixed it locally in a different way when I made changes to the spawning system so that massive hordes of weaker enemies can still spawn at high evolution values. I'll see if my UPS can keep up at late game :D )

Good idea! I uploaded a new version of the mod with your suggestion to add an extra "small" at the start of the size arrays. Should also result in bigger swarms because the small ones cost less pollution.

I've updated the mod to use the same spawning system as the vanilla game, which also fixes this problem. Medium biters now start appearing at 20% evolution and small spitters start at 25%.