Thanks for the suggestions. I'm looking specifically for 2D hand-drawn games. Strider 2 is a great game with a unique art style, but it's largely 3D and not what I'm looking for. Same with Klonoa and Tomba, although I haven't played either of those yet.
Astal, Silhouette Mirage, and The Adventures of Little Ralph all look great. I had the Megaman X Collection but gave it away because those games frustrate me so much. But I really need to track it down again. X4 does look very nice.