SimAnt

The Good
It's easy to learn. The mouse controls everything pretty well. The quick game only takes a half hour. You can get into harder levels as you want to. The manual is the most in depth work I have ever read about ants :) The developers went out of their way to represent an ant colony simulation. You have an infinite number of lives as long as your queen has eggs.

The Bad
The only thing is the full game takes a very long time. And once you get the dynamics of capturing an area you can apply the same thing to the hundred areas outside. The transition space to the house is ok. But there are too many repetitive spaces.

The Bottom Line
Well, you are an ant. You help your colony find food and make shelter. And you attack and defend against a rival colony in an attempt to take over the whole yard. And house :)