Good Side-Scrolling Shooter Games

Are there any GoodSide-Scrolling Shooter Games For PC? Games like Ikaruga

Trine.

Amazingly excellent side-scrolling goodness.

Trine was OK, got boring towards the end but I wouldn't say it was a shooter although I used the archer most of the time, did you? :D

Commander Keen

Trine, Commander Keen, and Earthworm Jim are all 2D platformers, not side-scrollers (which are a variant of shoot-'em-up).

Major Stryker, Raptor: Call of the Shadows, and above all Tyrian 2000 are easily 3 of the best side-scrolling SHMUPs you're going to find on the PC. You'll need DOSBox to play them, though, as they're very old.