I backed Coup on kickstarter a while ago and my game arrived the other day. A friend visited and we tried a few two player games which were both extremely short and somewhat lackluster, after twenty minutes (and three games) I was ready to give it up as a bad investment. Then we had a few more people come and join us and decided to play one more game.
We played dozens of games, more than I could count! Everyone had a really good time, ranging from hardcore gamers to one of my housemates who plays much less often. I'm still trying to work out what made it so addictive that we just kept going until we ran out of time.
Let me give a quick overview: At the start of the game you draw two characters representing who you have influence over. Each turn you take an action, limited by the characters you have available, to try to build up the resources to eliminate your opponents influence cards. Most actions can be countered by the right characters, any player can counter an action, not just the intended target. The last player with an influence remaining is the winner.
The twist is that you can claim your facedown cards as any character that you like and your opponents can call any move out as a lie. If nobody questions your claims you can act as if you have the claimed character (whatever it is) if someone calls you then you need to reveal a card. If you'd told the truth your opponent loses an influence, otherwise you do. That's pretty much the core of the game.
I had suspected that player elimination would be annoying or that people would quickly hit into either a dominant strategy or a "wine in front of me" style paralysis. Instead it remained entertaining for a good long while.
I think it comes down to using a game component that changes every game, which is to say the players themselves. Each game was different from the last because the information about the behaviour of the other players that had built up over the rounds had changed. It almost feels like a game that you've not really played until you play a bunch of rounds with the same people.
This approach never seems to keep as you increase the complexity of a game, while I can think of several deeper games in which players reputation is important and past experience drives gameplay, I can't think of one where it's pivotal. I'm also not sure that I can think of one in which the actions of a single game have much impact. I suspect that the tightness of the feedback loop made our evening of coup enjoyable, you could try something out, see the result and move onto the next game in ten minutes - it's harder to justify taking a risk on trying something new in a 3 hour game and it's tougher to learn anything form seeing one three hour game compared to seeing 18 ten minute games.
I also have to ponder what might've happened if more people hadn't shown up that day. I might have shelved Coup and not played it again in some time, or perhaps never again. By printing 2-6 players on the box of a game that really didn't feel well suited to 2 there's a risk of alienating a big part of the audience.
This makes me think about 404, in which the 6 player game has produced much more mixed reviews than smaller games (which have been met positively). It's not too late for me to write 2-5 on the box, but some players have genuinely enjoyed six player games and I wouldn't want to take that experience away from them. BGG entries record the number of players specified by the published and have a "best with" category, I wonder if that should become standard practice in the broader sense somehow. I can't see it being a good marketing move in isolation somehow.
I'm sure there's more I could say on the topics raised by Coup, but I think I'd rather run off and play another game See you next week.