Kula World. So you're this beach ball and you solve puzzles involving keys and fruit.
Katamari. So your dad who is the king of all cosmos destroys something and you have to rebuild it by rolling a giant sticky ball into...everything...
Final Fantasy. So it's basically remake Dragon Warrior or go bankrupt...great idea!
Farmville. So you...do...farming, and send your friends sad brown cows to guilt trip them into playing too.
Dino Crisis. So it's like Resident Evil only instead of slow moving, tension building zombies trying to kill you, it's huge, fast moving, people eating dinosaurs.
Mass Effect. So it's Star Trek only with more action and more talking, marketed to a large audience.
Assassin's Creed. It's a sandbox game in which you're laid down in a machine in the future thinking about killing people in the past.
I'm sure I can think of more.