The last 3 games I've played are Grid, Battlefield-Bad Company, The Godfather.
Grid's not bad. It gets a bit repetitive sometimes, you can't really do anything to your car apart from choose some brief colours, no tuning, no customising the car, both of which are unfortunate but you can deal with it. It's not overly hard, but there are a heck of a lot of different types of races, which makes it interesting.
Bad Company - It's pretty bitchin really, sorta like COD4, but I actually like BC more then COD. The story mode is pretty poor story wise, but it goes on for a fair while, just when you think it's over you have more missions. And it does that a few times. Though by far the best part is being able to blow pretty much anything apart. Jumping in the anti-air guns and blowing apart people/cars/trees/buildings is great fun, and it's good to just get out and blow your way through a house, beats finding a doorway
The Godfather - Sorta like GTA4 play style, but you take over 4 areas and do battle with 4 other mafia families. Pretty entertaining as well. Graphics wise it's nothing like GTA4, but it's fun to burn around in cars from the 50's, and starting mob wars.
Though, I haven't really played much lately, last weekend was about the first time in 3-4 months that the PS3 actually got turned on.
I didn't really like GT5 prologue much, it's fun to burn around a bit, but it's essentially a larger demo, a large amount of cars, no customisation, only a few races in free mode. Eh, I preferred Grid.
Dirt was pretty entertaining, simple though. Same company that made Grid, and they both play similarly, although dirt is obviously rally, grid is jap/euro/american racing.
Assassins creed is apparently alright, but gets repetitive after a few missions, maybe one to hire out rather then buy?
Another somewhat entertaining game is Lego StarWars. It's star wars, in lego. What's not to like

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