Xbox 360 games

can anyone help my buy deciding which games I should buy
I have already decided on modern warfare 2 and halo 3 and ODSt and fable 3(when it comes out)
I am looking for games where you can roam around a map instead of during missions
any game would be...

helpful

My games are (the high on the list the more roaming elements it has)
Fable 3 (I like the become the king idea they have)
Assassin's Creed 2 (if you played the first one you will know why)
BioShock 2 Sea of Dreams (nothing special with this game ………………………………your hand is a giant drill you say and you play as a big daddy…………..it’s like a sea of dreams coming true one by one)
Splinter Cell Conviction (I love the new gun fighting elements)

Grand theft Auto 4.
Saints Row 2.
as you may have noticed I like 18 or over games..haha

hiya my lil bro luvs his xbox he plays gta4 all the tym on xbox live and itz amazin itz also gd without live :}

halo 3 comes with odst if you didnt know.

Your list of games sounds good.