Games to play before you die

OPM has a stacked feature on 1UP called "Essential 100: PS1, PS2, and PSP Games You Must Play Before You Die." It's ordered by date starting at 1995, so naturally you won't find the PSP titles until the end. However, two undeniably potent games they include for the Sony handheld are Lumines and GTA: Liberty City Stories.

What PSP titles would you have included in the list?