I would suggest LittleBigPlanet if thats something you might be into, its a little strange but very fun.
I never played the MGS4 demo but I absolutely loved the game :D
Im a huge MGS fan though so I may be a bit biased :P
Platinums: Red Dead Redemption, Killzone 2, LittleBigPlanet, Terminator Salvation, Uncharted 1, inFamous Second Son, Rocket League