Alright.
Combonations to send out more units in an interesting and fun idea, however, though I did not find myself willing to play the whole game through I was sort of irritated with some of the factors.
1. Faster then the computer just gets boring after awhile. True the genre requires less of strategy and more of quick-paced do this now!, but I found that this isn't quite captivating for me.
2. The 'earned in battle' amount of money recieved was annoying because instead of informing me what I 'earned in battle' it was an account of my total money.
3. Though I am not quite sure how this played out by the end of the game, but I found it actually easier not to use any upgrades at all in the beginning. Gave me the advantage of not having to worry about too many different types of tiles.
That's all I have as I didn't work with the game long enough. I do hope you mind my criticism though as merely my own opinion, after all, that is what it is intended to be in order for your game to get its appropriate review. Take care and do well, you have potential.