What PS3 (not PS2) games are 'must play'?

[listic]

I never owned a console, and I'm going to stay with a friend who has a Playstation 3 (no PS2 compatibility, though).

What games, beyond Ico and Shadow of the Colossus (I see they were re-made for PS3) are "must play"? I would be ok just watching them play.

Can I just burn the proper ISO on a DVD on my PC or does running a pirated game require a hacked PS3?

[Michaël Samyn]

I have no idea how to run pirated games on a console.

But I recommend downloading Noby Noby Boy from the Playstation online store.
And of course flOw, Flower and Journey!
And Linger in Shadows.

I also think Beyond: Two Souls and Heavy Rain are worth playing.
LA Noire has its moments.
For a bit of silly pretty fun, Bayonetta is great.

[Benjamin]

I was pleasantly surprised by Knytt: Underground (for the most part). It really subverts some "quest" conventions, and is at points pretty upsetting (and of course pretty funny).

If you're willing to put in 40+ hours into something, I really loved Fallout 3. The game's story isn't great at all, but exploring the world and helping non-story–related characters is really rewarding. If you want to explore but not for 40+ hours per say, maybe you should try Minecraft! (I think that's available for PS3 now.)

I would second fl0w and Lingers in Shadows, too.