On the rainslick precipice of darkness (episodes 1 & 2)
I've been playing the Penny Arcade games recently...I finished episode 1 in a day and a bit (it's like 4 hours) and just started episode 2. The games are a mix of RPG elements (levelling, items, etc) and Final Fantasy style semi-real time turn based combat. Those aren't really what give them their 'oomph' though, the real fun is in the dialogue and the setting. If you know PA you can get some idea of the verbose and often hilarious dialogue, and the setting....well let's say that episode 1 was a weird cross-breed of early 20th century gothic style (lovecraftian), phallic, macabre and pee jokes and mimes and clowns. Seriously, if you read that and think "wot" you probably shouldn't be playing these games. The hand-drawn 2D graphics look great too.
I actually enjoyed episode 1 quite a bit and am now playing episode 2. If they are on a sale (as I picked them up) they are a total recommendation.
http://store.steampowered.com/app/18000