Feature request: Round Robin Tournaments needed

Hello,

I know, according to the FAQ there are no plans to implement Round Robin tournaments. However, I would be really glad if you can rethink this decision. Especially now that many chess clubs have their meetings on Lichess and would like to play club tournaments there Round Robin is absolutely needed.
There are often not enough players for a good Arena or Swiss Chess tournament and organizing these by hand is very tedious. Playing Round Robin with many Swiss rounds also is a problem, because it feels strange, the fine rating is off and also many times the last round cannot be played.
Also, as a trainer, we would like to let our pupils play against each other in Round Robin, so that they always play against others with equal strength. This is another reason why we need them. At the same I have heard from many other trainers and players from my region (South-Germany).

I know that there is this problem what to do when a players leaves, but this is rarely a problem in this cases. Maybe only allow it as a team tournament?

Push to top...

i don't know how but ok.

An interesting question. I suppose that, if round-robin were added as a tournament type to Lichess, it would need to be set up such that people cannot late-join. And as for "it has no fair way of dealing with people leaving the tournament early" - how is scoring that person's remaining games as losses not a fair way?

But round-robin works very well for correspondence tournaments, with all the games being played simultaneously. Another place has corr tournaments which work in exactly this way.

But maybe round-robin could be subtly incorporated into the existing Swiss format. A couple of observations:

* If only 3 or 4 players join a Swiss then, assuming it was set up as 3+ rounds (I don't know what the minimum is) it's forced to end up being a round-robin.

* 5 rounds with 5 or 6 players will usually likewise end up being round-robin. The exception is when, if the players are arranged in a hexagon based on whom they played in the first two rounds, all the 3rd round pairings go straight through the centre. When this happens, there is no possible way to pair round 4 without repeating a pairing, and so the torunament aborts. (The documentation is still wrong about this last point - see lichess.org/forum/lichess-feedback/swiss-tournament-ended-prematurely?page=4)

What could maybe be done is to add an exception to the Swiss pairing algorithm such that a round-robin pairing algorithm will be used in its place if these conditions are met:
* r >= 2 * ceiling(p/2) - 1, where r is the number of rounds and p is the number of players
* no new players have joined or left the tournament since it started (or only 1 player has withdrawn and p was originally even) - so that if late joins/withdrawals mess up the schedule then it reverts to a Swiss

But whether that would be a good idea I'm not sure.

For those of you who are interested, I have made Google sheets for running round-robin tournaments with 5 to 10 players, which I use to run such tournaments in my club. Please PM me if you're interested.