Resident Evil 4 (although it has gotten harder over the years. I have to keep coming up with different ways to warrant a replay. No-yellow-herb run, no merchant run, no other weapons besides starting pistol run, knife only run, no saving run, no explosives run, only shotguns run, and so and so forth)
Metal Gear Rising: Revengeance (the stun-parry is pretty hard to master on the higher difficulties)
Uncharted 2: Among Thevies (The Cheats in this game are hilarious)
Tomb Raider Legend, Anniversary, Underworld and the 2013 reboot ( I'm not going to lie; the fact that you stare at her ass for most of these is a big reason why I keep replaying them)
Metal Gear Solid 3, Peace Walker and 4 (really great stealth games with lots of unlockables. The codec conversations are pretty funny too.)
Probably some more that I am failing to mention.
Were they so debased as to recruit fledglings from the desiccated corpses here interred?