I already posted this in the "What are you playing" thread, but it's simply so good that I had to do a separate thread to pour some more love on it.
It's a free turn based multiplayer strategy game for iOS devices (no Android version yet it seems), where your objective is to either take out all the opponents units or destroy their crystals. You then have 5 moves per turn, where you add units from you pool, move units, use upgrades on them, attack and so on. There's a finite amount of units, and way its balanced then it pretty much always ends up being a matter of eliminating all the opponents units rather than taking out the crystals.
Anyway, highly addictive, got like 10 people at work hooked on it already. It's pretty disruptive for your productivity as well 
Give it a shot, I'm "Mazy" in it 