Burnout (the only I have) - it takes time, but it's fun and not definitely so difficult...
The only challenges to remark:
- you have to have camera (also required for Eyepet
- on-line challenges take time and you have to have luck for "skilled / informed" mates (like when you need 8 players to meet at the Stadium, 7 are already there and one is going the other way (and time is running...))
However overally really easy / achievable Platinum (if you like Burnout racing