Quote by FastRewind:
I would rent Avatar,Madden NFL 07,and Marval Ultimate Alliance. I would buy Galaga,King Kong, and Timepilot.
Not Madden 07! That's the only one that's not an easy 1000!
Madden 06 has the 400pt. achievement for simming 30 years of franchise. That takes around 5hrs. NBA Street: Homecourt is fun and easy. NHL and MLB 2K6 are easy as well! If you're good at football, then the NCAA games are easy! NBA Live 06 is an easy 960!
Then there is Cabela's Big game hunter, Chronicles of Narnia, Fable 2 (I can get you about 600 points in less than an hour!) Viking is pretty easy and fun, but a little more time consuming than the sports games.
These should definately get you to 20K. If you have the resources, This list, combined with the list in Raine's post could have you over 30K! lol
I haven't looked at your played games, so I don't know which of these you have played yet! Happy hunting!!