This is a good game, but I will admit that the graphics could be better. I also did not like it how you couldn't even seem to know where the money you had was. I couldn't see much with the screen blocking the question marks. Still, it's nice to play. It's mostly because of how simple it is and how it's fun to just blow stuff up. I like how they blow up when they hit your fortress.
Apparently, I needed money for the mines or anything else. The sound effects were pretty good. It's just that you used some easy text for a lot of things. It still is pretty good for a time waster. You might want to put more variety into the enemies too.