I'm a big fan of the game Zendo. But I don't think it suits large groups very well. The more other players there are, the more time you spend sitting around; and you may well get only one turn. I also think a game tends to take longer with more players.

Here's an alternate ruleset you can use if you have a large group. I think I've played it 2-3 times, with 15-ish? players, and it's finished in about 30 minutes each time, including explaining the rules to people who'd never played Zendo before.

For people who know the typical rules, here's the diff from them:

• After the initial two samples are given, players run experiments¹ in real time, whenever they feel like they have one they want to run, and the universe marks them. There's no turn taking, and no need to wait for one player to finish their experiment before you start constructing yours. Just try to make it clear when you have finished.

• At any time, a player can guess the rule. They announce clearly that they want to guess, and then play pauses until they're done. If they take too long, the universe should probably set a time limit, but I don't think this has been a problem.

• If they guess correctly, they win. If not, they can no longer guess. The universe provides a counterexample, and play resumes.

• I've never run out of players before someone guesses the rule. Two options would be "everyone gets their guess back" and "game over".

Another change (starting from the standard rules) that I think might speed games up, is the ability to spend multiple funding tokens to publish a paper out of turn. But I've only run this once, needing three tokens, and no one took advantage of it. Maybe I'll try with two at some point.