Round robin is not a good tournament format in general. It takes way too long and it’s especially prone to corruption.
- Single elimination. Fast and problem-free.
- Double elimination. Slow, but people get to play more games.
- Swiss. People get to play the most games, but no exciting finals.
- Swiss, then cut to single elimination finals. Our recommended format, but see below for issues.
- Round robin. Crazy because it takes too long and is riddled with corruption issues.
There has to be a balance of letting people play enough, yet also making the tournament EXCITING, and not take forever. If you want pure speed, single elimination is the best. If you want to have everyone play the most, swiss is best, but it’s really boring because there’s no “finals” for anyone to watch. The best balance of these factors is swiss for several rounds, then cut to top X single elim (X = 2 or 4 or 8 depending on how big the tournament is).
Magic the Gathering came to this same conclusion. But you have to be aware that “Swiss then cut to top X” inherently has corruption problems and a horrible problem where people “intentionally draw” all the time instead of actually playing. MtG tournaments are plagued by corruption and intentional draw. In our tournaments, we don’t have that because we don’t accept match draws at all (a game draw is ok, but not a MATCH draw). There’s a tie-breaker procedure (which hasn’t been established for Codex, but surely it’s remaining HP as the first tie-breaker and probably sudden death turns until anyone’s HP goes down after that). And intentional draw by both players is not a thing either because it counts as 0 points for both players, so there is no reason to ever do it. This doesn’t solve all corruption problems with the format, but it greatly minimizes them (far more than in MtG!) and the result is you get to have the hype of a finals everyone watches and the fun of all players getting to play several games in early rounds.
Be aware that this system does add hours to an event though. If you cut to top 8, that means 3 more rounds (3 more hours, because a round is 50 minute + 10 minute break). If you cut to top 4 that is ALSO 3 more hours because it’s 2 more rounds (+2 hours) and ALSO there must be an additional round of swiss before the cut. Cutting to top 2 for a finals is, again, 3 more rounds. 1 round for the finals, but you must do TWO more rounds of swiss before the cut, for it to even mathematically work. This part is a standard, not special to my rules.
This document is old, but still gives correct info on how “swiss then cut to top X for single elim” works.