Do note that often times this is a tactic the AI employs, simply walking back and forth to dig, when it no longer feels that walking through your nicely designed deathtrap entrance is the most intelligent choice, but lacks a digger.
Plus, this isn't necessarily a detraction from the game. With more dynamic terrain, you're forced to take terrain as a liability. You can't just plunk your brain under a mound of earth and watch as your enemies hopelessly try to reach it since they have to stand still at a mound digging away at it for a few minutes (IRL) just to reach your brain.











