P:

Pac-Man - Xbox Live Arcade
http://xboxamerica.com/games/209/Pac-Man

Pac-Man Championship Edition - Xbox Live Arcade
http://xboxamerica.com/games/455/Pac-Man-Championship-Edition

Paperboy - Xbox Live Arcade
http://xboxamerica.com/games/79/Paperboy

Penny Arcade Adventures: On the Rain-Slick Precipice of Darkness, Episode One - Xbox Live Arcade
http://xboxamerica.com/games/553/Penny-Arcade-Adventures:-On-the-Rain-Slick-Precipice-of-Darkness,-Episode-One

Perfect Dark Zero - Shooter
http://xboxamerica.com/games/120/Perfect-Dark-Zero

Peter Jacksons King Kong - Action
http://xboxamerica.com/games/121/Peter-Jacksons-King-Kong

Phantasy Star Universe - RPG
http://xboxamerica.com/games/185/Phantasy-Star-Universe

Pimp My Ride - Racing
http://xboxamerica.com/games/257/Pimp-My-Ride

Pinball FX - Xbox Live Arcade
http://xboxamerica.com/games/379/Pinball-FX

Pirates of the Caribbean: At World's End - Action
http://xboxamerica.com/games/244/Pirates-of-the-Caribbean:-At-World's-End

Poker Smash - Xbox Live Arcade
http://xboxamerica.com/games/530/Poker-Smash

Possession - Action
http://xboxamerica.com/games/36/Possession

Postal III - Shooter
http://xboxamerica.com/games/304/Postal-III

Prey - Shooter
http://xboxamerica.com/games/42/Prey

Prince of Persia Classic - Xbox Live Arcade
http://xboxamerica.com/games/408/Prince-of-Persia-Classic

Pro Evolution Soccer 6 - Sports
http://xboxamerica.com/games/262/Pro-Evolution-Soccer-6

Project Delta
http://xboxamerica.com/games/64/Project-Delta

Project Gotham Racing 3 - Racing
http://xboxamerica.com/games/94/Project-Gotham-Racing-3

Project Gotham Racing 4 - Racing
http://xboxamerica.com/games/337/Project-Gotham-Racing-4

Project Offset - Shooter
http://xboxamerica.com/games/158/Project-Offset

Project Sylpheed - Action
http://xboxamerica.com/games/281/Project-Sylpheed

Pure - Racing
http://xboxamerica.com/games/533/Pure

Puzzle Quest: Challenge of the Warlords - Xbox Live Arcade
http://xboxamerica.com/games/484/Puzzle-Quest:-Challenge-of-the-Warlords

Puzzle Quest: Galactrix
http://xboxamerica.com/games/539/Puzzle-Quest:-Galactrix