While it's nice to have infinitely high difficulty, it may be nice to cap it. 

Particular issue:  I ran ramp with spikes with no enemies but ubers, as a way of fighting them specifically.  A fish then spawned much later and proved to be the harbinger of the apocalypse, as this spawned enough ants that they couldn't harvest the fish properly, and I couldn't kill them, so my game crashed. 
And on the sixth day, God created ant in his own image, and gave them dominion over the earth and all of its creatures.  Amen.