The best casual games like Stumble Guys are Fall Guys, Gang Beasts and Ultimate Chicken Horse. Below are 8, each with the reason it is here — and, at the end, what filtering to casual costs you.
Filtering to casual means you want something you can put down. That is the whole definition, and it says nothing about how deep the game is.
What you get: A game that fits around a life. Short sessions, save anywhere, no penalty for a week away.
What made Stumble Guys worth playing in the first place is covered on the full list. This page is the casual part of that answer, and only the casual part.
The game this is answering, free now, and the obstacle design is far better.
The same wobbly-physics comedy, aimed at a sofa instead of a lobby.
Party platforming where everyone builds the level that kills them.
Physics comedy as a co-op puzzle rather than a race.
A board game that keeps stopping for minigames designed to end friendships.
Brawling with the same deliberately awful physics.
Free, cross-platform, and easy to get anybody into.
Co-op chaos where the stress is the joke.
Momentum, sometimes. A game designed to be left is also a game that is easy to forget you were playing.
Specifically, these are strong answers for Stumble Guys that are not casual games, so they are not on this page:
The full list is on games like Stumble Guys — 10 picks, no genre filter.
Fall Guys. The game this is answering, free now, and the obstacle design is far better.
No. Stumble Guys released on the PC & Modern Multi-Platform, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
No. Several of the deepest games there are — Tetris, Balatro, Into the Breach — are playable in twenty-minute pieces, and some of the shallowest demand an entire evening.
Often the opposite. Many are built around daily timers and streaks, which means stopping does cost you — the one thing a casual game is not supposed to do.
By hand. Each pick was written for the full Stumble Guys list first, on what the game actually does, and this page is the part of that list that is casual — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the casual guide for where to start in the genre generally.