Challenging game. The instructions are unclear, but after trying a game I understood how it worked. The reaction time of the computer can make it very hard to win, but it is not impossible. It was also not clear immediately that I could cancel what I bought, I think it should also cancel if you click on another unit. One "bug": if I bought a unit and waited until I had 30 power, I could cancel the unit and get 40 power.
I enjoyed it.