Gets kind of annoying hitting "esc" to pause your game and then hitting ok to go back to your game only to find out you just quit your game. At least add an "Are you sure?" dialog.
Physics are far from "Spot on." The balls do not correctly react when they come in contact with the bodies. Momentum does not seem to be lost on contact.
The game is way too dependent on your upgrades. You should have a choice of what upgrades you want to take, not be forced to take a certain path to beat each mission.
Some people may disagree with this, but you may want to make it so ships dont drop any money when you collide with them and kill them. All I am doing to farm money right now is suiciding my plan in to the ships and collecting like 4k each time.
Level two just increases the difficulty way too much. There needs to be some sort of a prediction element for which way the characters are going to move and how fast.
Enjoyable game, but it would be nice if you had more upgrades, and larger stores. Once you get to the biggest store the game is pretty much over.
Very enjoyable game though.