SamuraiShyGuy wrote:
None of those sound like what I'm thinking of. Perhaps I'm crazy or Gain Ground really is what I was thinking of. And I heard that game's pretty bad.
I liked Gain Groud. And it's still on the Wii Shop here in EU.
It's pretty good and straightforward co-op action strategy with simple and unique gameplay and cool variety in playable characters, different weapons, stages and enemies.
It's rescue everyone (bring all your characters to the exit) or/and kill every enemy in each mission. I think it has 50 or 60 stages (single screen) Good leveldesign, a few bosses, and a lot of traps so don't always rush forward. I thought it was exciting and challenging playing this with a friend - until we finished it and put in our names into the highscore list. I really liked this game. I want the 3-player arcade version 
I never had a Mega Drive back in the day, and never heard about this before it hit the VC. Glad I took the chance and spent 800pts on it.
Now how's Crack Down? Looks good.