Elo sucks – better multiplayer rating systems for smaller games (2019)
Elo is great for what it was built for: ranking chess players. Chess is (1) extremely low-variance, (2) has an extremely high skill ceiling, and (3) is 1-on-1. Elo works great for chess, but it would <i>never</i> work for something like Poker. Let's briefly go over these three points.<p>Most games aren't chess -- where the only variance is picking who's black and who's white -- in fact, they might include dozens of RNG mechanics (from critical strikes to ability rolls, to spawn points). These mechanics (while fun and well-designed) might pollute your "idealized" model. There's also the problem of RPS (rock-paper-scissors) mechanics or pick-counter-pick mechanics which will also heavily skew win rates. For instance, given a slow combo Magic deck, you will most likely auto-concede to mono red aggro (regardless of skill level). If you're using Elo, this will pollute your model. (Hint: you shouldn't be using Elo.)<p>Most games also don't have chess' high skill ceiling. Chess has such a high skill ceiling for a number of reasons -- it's one of the oldest games still being actively played, for one. Suppose your "game" is simply the flip of a coin (everyone wins 50% of the time). Zero skill involved. Trying to model win-loss-ratios using a sigmoid curve is silly. Obviously, no game is going to be a coin flip, but there's a world of difference between chess and DOTA.<p>TruSkill attempts to fix (3) by using clever Bayesian updating on a player-by-player basis[1] but in reality, it's a shit-show. Using Elo (or variants thereof) for team-based games where the team isn't really a team (more like 3-5 random people plopped together for one match) is incredibly misguided, but continues to be implemented in just about every modern multiplayer game (to the players' frustration). Of course, mixing and matching pre-made groups with non pre-made groups creates as many issues as you might imagine.<p>In short, why so many game devs are enamored with Elo when it comes to ranking is a bit bizarre.<p>[1] <a href="https://www.microsoft.com/en-us/research/wp-content/uploads/2007/01/NIPS2006_0688.pdf" rel="nofollow">https://www.microsoft.com/en-us/research/wp-content/uploads/...</a>