I'm going to agree with Mike_intellivision but up it a bit
Make it a good game
Make it a unique experience
Make it a game your audience is interested in
Make sure they know about it
The infamous Psychonauts and Okami are testiment to this. Great games, unique, people knew about them, they just weren't the type of games people were looking to play.
TvsC looks to be an excellent game (I'll own it shortly) but it's hardly unique, even on Wii, and I doubt most Wii owners will care, sadly, even if they did know about it. Really this game should be an easy million seller. Anything less is a shame.