Awesome question - I'll copy and paste u/FallGuysJoe's answer from a blog post he wrote earlier this year:
1. 60 players creates the perfect amount of chaos. When we first started working on Fall Guys we had to ballpark our player count based purely on what felt right to us, and 100 players became this talismanic number we decided to aim for. “100 players, 1 winner“ instantly gives players a sense of the mayhem they’re going to deal with, and two years ago was the standard for all Battle Royale titles (Fall Guys isn’t a battle royale per sé, but when explaining the game for the first time it helps to draw those parallels).
Once we started prototyping gameplay we quickly we found that players couldn’t really tell the difference between 50 and 100 contestants. Regularly we’d ask players “how many Fall Guys did that feel like you were playing with?” and their response was often twice as high as the actual number that were in-game with them. It turned out that we didn’t need as many players as we thought to create the crowds we wanted the gameplay to include.
We also began to find that 100 players made even our simplest levels too crowded and ultimately less fun. Players would lose their Fall Guy in giant bundles trying to fit through small gaps, and if we made our levels bigger they were too large and cavernous to feel cohesive. Once we reduced player counts to 60 we found the horde of Fall Guys still invoked all the craziness we wanted, but without any of the frustration and confusion that the extra 40 Fall Guys brought with them.
2. Better performance across the board. It also makes sense for us to aim to keep our player count as low as possible because a higher player count means more time spent matchmaking. We want players to have minimal downtime between Shows, and finding 60 players to play together have proved to be exponentially faster than finding 100.
On top of this we’re able to push both our networking and rendering budgets further with less objects on screen. At launch, players will be able to experience more accurate networking and more detailed visuals- 40% more in fact! (note, this number is made up by me and is in no way backed up by engineering or art teams).
3. More wins for everyone! Your chance of winning just jumped from 1/100 to 1/60! We want Fall Guys to be a game anybody can pick up and enjoy, and by reducing our player count slightly we’re able to get more players through those early rounds and ultimately give everyone a better chance of leaving with the crown in their hands. We want everyone to feel like they’ve got a fair shot at victory (yes, even you).
Ultimately we’re still in development and things could change between now and launch, but through extensive playtesting we’re finding that 60 Fall Guys strikes the perfect balance of chaos and fun. We believe it’s going to create the best experience for players when they get their hands on the game during closed beta, and ultimately when the game goes live this summer.