Of all the games I have on my Droid, this is easily the most addictive. I have had it a couple weeks now and play it daily. Thought I'd share. Source Here's the QR Code for the free version, which is endlessly playable. I'm planning on buying the full game in the near future. The one thing the game could use is a multiplayer mode. As it stands, the game is pretty challenging even on medium difficulty, and the free version actually has a decent number of options to tailor the game as you see fit. Check it out.