God of War: Chains of Olympus
(Sony, 2008, Metacritic Score: 91)

Kratos brings his Blades of Chaos to the PSP in a chapter that bridges the gap between God of War II and the upcoming PS3-quel. The series maintains all of its epic scale in transition to the portable, as you still run around huge environments, solve complex puzzles, and battle gargantuan bosses during your quest to find someone from your past. If you want blockbuster action on the go, look no further than Chains of Olympus.

Grand Theft Auto: Liberty City Stories
(Rockstar, 2005, Metacritic Score: 88)

Journey back to Liberty City and take on the mob with an all-new Grand Theft Auto game built specifically for the PSP. While a bit outdated now that GTAIV has rewritten the rules, Liberty City Stories still provides a massive city, a ton of missions, and enough extra activities and side quests to keep you busy for a long time. The game also includes a full multiplayer suite to keep you and your buddies occupied, and there is always Vice City Stories on PSP to keep you busy after you finish this one.