Nice, but as said, needs some serious balancing in the costs of xp or make the damage and airstrike less good.
After getting al the upgrades it's really boring...
Maybe throw in some stronger enemy's.
I've got it now about two or three times that I attack with the shaman and the item that gives 80% change of 2 poison dmg for six turns that didn't stack. The other player was also the shaman. Does healing have anything to do with it? Because that's described nowhere in the skill part.
Only comment yet: implement the 'get a card when you win' thing differently. Now it is by chance and that way some real nitwit can get five cards while others who win way more only get two or so. I think it is really unbalanced.
So instead I suggest you get a card with every so much wins, or at reaching a certain level.
Great game, and to everyone having a hard time: get the flak and shield siphon first. This way you can let the flak go all the time while recharching it's shield with the shield building. Really, really helped me out. Then just upgrade those two (you get massive amounts of resources) and after your main base, then the rest, or that's how I did it :P.
I like the game, but don't really get the fuel thing :P. And maybe you should make the turbo power-up timed, just to make it a bit harder. I think it is pretty easy with turbo and gun :P
Brilliant game, just like four second frenzy series. Like the stress and need of fast reflexes.
Only bad thing I could discover: the game with the avoiding the green balls is way too easy. At 4.0 everything except that one was gone, and made it easily to the five. :P