- Players start with 10 days (240 hours) on the clock.
- An additional 3 hours are added to the clock after each move.
- If you run out of time you lose, unless the board position is such that it would be completely impossible for your opponent to checkmate you, in which case you draw.
- It's up to each player to track their opponent's clock and point out if they exceed it, and they must make that claim while the game is still otherwise in progress.
Then, since 10+ days is a long time to sit around waiting to claim victory if your opponent has flaked, we can additionally say players must make at least one move per 3 days (or whatever) or else they are considered to have forfeited the game, and that if a player forfeits two games in this manner then they are removed from the tournament and none of their games are counted in anyone's score. This ensures players aren't punished for having lost earlier on to someone who later flakes.
If we limit to two games at once, then with 8-9 players we can expect a single round-robin to conclude within something like 4-5 months, which seems reasonable. With 10-13 players I'd say we should play three games at once, and with more than that I'd say we should reconsider the format.