Money tower upgrades are completely imbalanced. Original tower = 150 for $3/tick. Upgrade 1 = 400 for $4/tick. Upgrade 2 = 1500 for $4/tick. What? Why would I ever get the second upgrade?
Also, the scoring on the collection levels is dumb. I should be rewarded for crushing the enemy and getting the stuff quickly, not for dragging it out and avoiding the things I'm supposed to collect. Maybe a timer, where you get bonus exp based on the time left.
Seems like you don't get exp for bonus points from nukes and shields. I maxed nuke and shield, went to level 1, and went from ~4k points to >20k points, but got 0 additional experience.
Game feels halfway done. Needs more pickups, more stuff to avoid (both more types and more of them on the screen). Explain powerups. Make a destination, something you're trying to do.
Great start to a game - relaxing, great look, etc. But needs some interaction with the world, or there's absolutely no point. As you collect more guys, they should change / restore / activate the alters, so there's some goal besides looking around. But great start to a game.