- Shadow Complex is like a mix between Contra and Super Metroid for XBLA. I highly recommend it.
- The Red Star is like those games, but with more of a Double Dragon perspective -- as in planed 2D. Very good game, though my buddy and I couldn't beat a boss very deep in.
- Might be redundant, but for 2D gaming, nothing beats the GBA and DS Castlevania games.
- The DL-redux of Bionic Commando is along those lines as well.
- Alien Soldier is a Treasure Mega Drive/Genesis shooter that runs about $200 in Japan, but is on Wii's Virtual Console.
- Timeslip is a little-known shooter for SNES that's Contra-esque and fetches a very low price on eBay.