Here are a couple of “stalking stuffers” for you!
Arryon’s GUARDIAN is a pretty standard vertical shoot ‘em up, although I really like the chunky pixel graphics. Shields that take multiple hits and are readily available to the player make this one a bit easier than it should be, in my opinion. But otherwise, it’s nice. The source code (Game Maker) is also available from the link above. (Source: the2bears)
I like the main mechanic in Shooo’s POPGunner: you can fire Polarity Orb that bounces off both the top and bottom of the screen. Every hit that you get with it raises your multiplier and you can get extra points for hitting the enemies from behind. It’s fun in practice – I’d love to see more done with the idea, though.