I highly recommend the Rampant mod. It makes the biters smarter (they'll seek out the weaknesses in your base defense), let them use pheromone trails and condu

I highly recommend the Rampant mod. It makes the biters smarter (they'll seek out the weaknesses in your base defense), let them use pheromone trails and conduct pre-emptive raids on your base, and makes them tougher in general. Depending on what you have to fight them with, the default settings of Rampant might be too difficult, in which case the mod has lots of options that'll let you dial that difficulty down. Also, you can get various other mods (like improved weapons, far reach, or tweaked evolution rates) to make fighting them easier.