Radien X

This is just a beautiful 2D vertical-scrolling shoot-'em-up, complete with weapons, upgrades, bosses, and fantastic gameplay. And, if you don't like the side-scrolling action of Platypus, but are looking for something with (just a bit) more depth than Galagon 2004, you could be in for a real treat.

In case it isn't immediately obvious, your mission is to avoid enemy fire while blasting away at everything else, and the key to this is picking up the glowing square cubes, each of which powers up one of your three weapons - the red vulcan gun, the blue laser, or the purple electric-spark plasma ray (powerups with letters on give you auto-firing missiles).