This game is awesome under my personal rating's, it is called sauerbraten, or cube 2 if you think thats hard to say. sauerbraten is a first-person-shooting game, with a level editor mode. I'm not too detailed in information about this games' editor, but I know all about the shootin' part, I recommend you try it, and trust me you go 200 fps easy on your grandmother's rig, you should be able to run it. Link to website: http://sauerbraten.org/
