I want to get a girl to talk to me on Valentine's Day for a game
Why don't you just talk to her like you normally would?
She's so pretty and I always give up before trying to talk to her.
That's good you found someone you're attracted to, but you shouldn't be too nervous to approach her, even though it's natural to feel that way. Just think, that even if you have a slim chance of success, that's still better than the zero chance you have if you don't approach her.
Yeah but I don't want to fail and turn her off so I'll try a different approach.
I think that just being yourself is the best way for you to avoid failing. If you are being deceitful by pretending that it is a game, she might detect the insincerity, and that would probably turn her off more than anything you could have said if you were just trying to be nice.