minecraft,
it's a creative game where you can walk around and build, just about anything

download DOSbox and games
DOS games are usually relatively small so you shouldn't have any trouble downloading them
here are some links
http://dosbox.com/
http://www.bestoldgames.net/eng/dosbox/
http://www.classic-pc-games.com/pc/index.html
here is a tutorial on how to use DOSbox if u need it
http://www.classicdosgames.com/tutorials/dosbox.html