Microsoft's XBLA service features an online downloadable version of 1 vs. 100, the popular TV game show where one contestant tries to out-answer a pool of 100 people. It's currently in a semi-open beta mode, available only to XBox Live Gold members; it's not clear whether that will change once the code is finalized and sponsors are lined up. As there are in-game commercials, a pay-to-play approach doesn't seem like the right long-term model.
I've been playing this a little bit recently, and it's nicely handled. There are two modes -- a non-hosted, non-prize version where there is no "One" and it's just a pool of crowd players (often in the tens of thousands) competing to answer trivia questions quickly and correctly. Then there are the official live-hosted versions, which play more like the TV show, though spectators in the crowd can still answer questions and have a (small!) chance to become part of the One Hundred or even the One; the prizes are free XBLA games and Microsoft store points. In-game, players are represented by their Avatars, and it's quite impressive to see a hundred of them on the virtual set.
Games always start at scheduled times on XBLA's Events calendar, and are not constantly available, which makes them seem more like an event worth attending. Players can drop in or drop out at any time, which is valuable because the beta game system isn't completely stable or ready for high user volumes -- there are sometimes tens of thousands of players connected, and the system appears to be having trouble dealing with all the data shuffling in real time. Sometimes it's hard to join a game in time for the first question, or at all, and sometimes players disappear unexpectedly. I've even seen The One disappear partway through a live game. One wise design choice -- the commercials the sponsors run don't appear to stream live; I believe they are downloaded to the XBox hard drive with the game client, as there are only a few different ads that repeat frequently. I also suspect that the questions themselves may be downloaded as the game starts -- it wouldn't take long to do that, and it would conserve bandwidth for handling incoming answers and outgoing updates at the server end.
The game's questions are varied and fairly challenging -- some can be answered by process of elimination if you have any clue about the topic, others require fairly in-depth knowledge. All are answered with a single button press of X, A, or B, with Y reserved for earned skips in regular play and for The One to use assistance options in live-hosted play. The questions are displayed on screen, not read aloud, most likely for speed and bandwidth efficiency, and some "shows" feature community-written questions submitted by XBLA users, which is a nice touch. The demographics of XBLA at large do come into play on the answering end sometimes -- I was shocked that the majority of players one evening couldn't select the correct size of a 45 RPM vinyl single from a set of three answers (3", 7" and 12"), but then I'm old; my guess is when most XBLA-era gamers think of vinyl they think of 12" albums, so it's an honest mistake. Most games I've participated in seem to indicate that videogamers are a pretty smart bunch, or at least that our brains are wired to organize non-essential information for efficient retrieval.
Saturday evening I played a couple of rounds with a visiting friend who's very good at trivia games -- the game supports multiple players on one XBox Live account, so we competed against each other, the two other players in our system-assigned online grouping and the rest of the audience. It's not a great party game in that regard -- unlike, say, Smarty Pants on the Wii, there's no immediate sense of fun and competion against the individual sitting next to you; it feels no different from competing with other XBLA players. But Microsoft's doing a nice job moving into the casual segment with this effort, certainly beating Nintendo in this niche (the WiiWare entry TV Show King doesn't have online play, or an online source for fresh questions.) I hope to see more of this kind of thing on XBLA in the future, assuming, of course, that they're eventually able to get 1 vs. 100 up and running in a stable, post-beta form. The TV model is appealing, but game shows where the lead contestant can randomly vanish are not ready for prime time.