Vastly improved biter AI behavior, tweaks biter expansion mechanics. Memento mori.
Mods introducing new content into the game.
Changes to enemies or entirely new enemies to deal with.
I seem to be spawning behemoth spitters in the early rush. The first rush magically despawned, the second rush was total destruction. Image below
http://i65.tinypic.com/2dalgeo.jpg
I have the same problem. Biter evolution is racing towards 100. In this screenshot i only placed two drills and played for 12 mins: http://i.imgur.com/KISqy5c.jpg Also got an error because of an empty inventory.
I'll take a look, it may be that 0.13 changed the evolution rate speed and it needs some more balancing.
Version 0.5.1 should fix this. Let me know if this is not the case.