Fart Together launches into Steam Early Access with a small set of modes built around the same shared-raft physics. The Early Access roadmap explicitly lists new modes as something the team intends to add, so the current lineup is a starting point rather than the finished set.
The headline mode. Two to four players share one raft and work through obstacle courses together, with the compounding physics applying to everyone equally. The store page describes it as controlling "your direction, timing, and gas" to make it through the courses - and warns that one player going the wrong way can send the entire raft off course.
Some third-party listings describe the supported count as 1 to 4, which is consistent with a solo player being able to take the helm alone. The Steam store page itself states 2-4 players, so treat that as the authoritative figure and solo as a likely but unstated option.
The versus mode puts up to 8 players on the course, split into two teams of rafts racing through the same course. The physics do not change - which is the point. A team that has learned to push in sync will pull away from a team of four equally skilled players who have not, purely because their raft accelerates cleanly.
This is the mode that makes the physics legible as a skill. In co-op, a bad group reads as a funny mess. In a race, a bad group visibly loses, and the cause is usually obvious in hindsight: too many people correcting at once.
Beyond the two core modes, listings and demo coverage reference a Free Mode for open practice on the courses and a Time Trial variant for running a course against the clock. Both are natural fits for the design - a time trial is really a test of whether your group can push in sync with no opponent to race, which is the purest version of the skill.
The Steam feature list confirms Multi-player, Co-op, Online Co-op, Split screen and Full controller support, with controller support for Xbox, DualShock and DualSense, plus a keyboard-only option. Third-party listings go further, claiming up to eight players locally in split screen. The core caveat is the one the store page prints in its system requirements: a stable internet connection is required for online co-op.
The Steam categories include Camera Comfort, Custom Volume Controls, Playable at your own pace and Playable without Timed Input. That last one is significant for this particular game: because the core loop is about coordinating timing with other people, having a mode with no timed inputs at all is a real accommodation for players who cannot respond on a strict beat. Steam Cloud and Family Sharing are also listed.
The plan communicated after the demo is to add more playable characters, more customization, longer and more challenging courses, and new modes. Currently the content is roughly 4 to 5 hours of courses. That is a reasonable amount for a party game that plays well in short sessions, and it is clearly the number most likely to move first.