My brothers and I used to play a computer game called Tank Wars. It was a game where you tried to destroy your opponent's tank by adjusting your tank turret's angle and velocity (while accounting for wind) and choosing the right weapon to blow them up. Depending on how well you did, you earned points that could be used to buy more advanced weapons. It was a really simple game that was fun because of the wide variety of game configurations and crazy weapon choices. (The five megaton nuke would destroy most of the screen, while the ball of dirt would fire... a ball of dirt.)
I thought about this game the other day and did a search for it today--and I found it! You can download Tank Wars at The 386 Experience. It seems to run ok under Windows XP, though a bit too fast to play on our 2 GHz Celeron notebook. Luckily, Tank Wars has some helpful configuration options: using the command line options
speed4000 falldelay2000 seemed to make the game work pretty well. Sherree played with me a bit and even admitted that it was more fun that she though it'd be.