Don't know if any of you know about or have played this game, but I've found to to be an excellent time waster, and since there is actually a native linux version I purchased the full game (I had previously only played the demos of the first games online.) It's a sort of RTS/Tower defense hybrid; and because of the built in map editor the thing has tons of replay value. Interesting thing is, I hate tower defense games, but I like this game.
I remember playing the flash version of Creeper World 2: Academy and some of the older ones, really fun games. I recommend playing the flash games to anyone looking at this series or is interested in it if Arc Eternal has the same concept, which is looks like it does. Click here to play Creeper World 2: Academy
3 is very similar to the first one, which I liked better personally, although I only played the flash versions of the originals.