Xenon 2: Megablast

Xenon 2: Megablast is vertically scrolling space shooter, in which you have to pass several levels, filled with waves of enemies, that all end with a level boss creature. Each group of enemies you destroy grants you a cash reward and every once in a while you enter Colin's Bargain Basement, where you can use this cash to purchase upgrades for your ship like better weapons, speed & health upgrades etc. Some upgrades can also be picked up during the levels.