So... to beat 2.2 just start putting normal lasers in the northeast until you run out of money. Then some more for measure and that keeps the green guys at bay long enough for your Thor missile to take care of them (I added another one).
I don't know why the guy below who said this got downvoted, it worked like a charm
Nice game, but repairing base at expense of experience would be a nice addition. Wave 14 or so got saved with <100 HP and no matter how much I upgrade my stuff can I kill all those huge tanks in time