I introduced some of my friends to Modern Art last night (or rather, tonight post-backdating) and we ended up playing it for 4+ hours straight. We started with a couple three-player games then ramped up to a five-player game as people showed up. Before we knew it, it was 2 AM.
Modern Art is an auction game by Reiner Knizia. Players vie to make the most money by buying and selling artwork. The catch is that the value of bought artwork is determined at the end of the round by the number of other artwork by the same artist that were sold. So players have to bid for artwork without knowing exactly how much it will eventually be worth. Especially when playing with newbies, this leads to hilarious over- and under-pricing.
Assuming you don’t play it regularly, the game really shines when you play a few consecutive games. People begin to adjust to each other’s tendencies and strategies, allowing for the surprise high-bid/low-bid or an occasional Jedi mind trick.
Having played the game with three, four, and five players, I think playing with five players results in the tightest gameplay. With more players, you get fewer cards and you get fewer turns, so you have to be smart about when and how you use your cards. With three players (the minimum), you generally get all the tools you need—e.g. a double-auction card for each artist—and your turn comes up often enough to let you swing the game when you want to.
(I backdated this by a day. Lame =/)