Seconded. One Night Ultimate Werewolf has been a workplace favorite for well over a year. Recently introduced it to my friends, who are into Mafia (though those games inevitably end up with people upset at each other) and it was a hit.

Some reasons ONUW is awesome:

- Each game can be completed in 5-10 minutes.

- Supports a very large amount of players. We've had 20+ players without any issues (with the expansion pack).

- As mentioned above, replay value is high. I still encounter new situations all the time.

- No need to have an individual sit out as an emcee due to an awesome mobile app that leads the round.

- Most importantly, does not seem to lead to interpersonal conflict the way Mafia tends to. Most likely due to shorts rounds and the fact that there's enough information to go off rather than pure speculation.