Big Walk supports 2–12 online players. Two is the minimum for meaningful progress, twelve is the maximum session size, and the developer says the game was not built around one ideal group size.
Choose the correct world version
When the host starts a session, they select a two-player, three-player, or four-plus version of the world. The official FAQ says some things change to adapt to that selection, and recommends treating the choice as the minimum number expected rather than the maximum allowed.
If one person may arrive late, choose a version the players already present can progress through. Friends can join after the host starts, but choosing a higher minimum can leave the smaller temporary group unable to complete adapted situations.
Solo and matchmaking limits
There is no single-player mode. One person can start a world and walk around, but the FAQ states they will not get far because the game is entirely designed around teamwork and talking.
There is also no online matchmaking. Big Walk is a long-form adventure meant for an organized group across multiple sessions, so players join friends rather than entering a random public lobby.
How friends join a session
Friends on the same platform can see the host's game through that platform's friend system. Cross-platform players, or players who are not platform friends, can use the short Join Code created each time the host starts a session.
Crossplay is officially supported across Windows and Mac through Steam, PlayStation 5, and Nintendo Switch 2. Progress remains with the host, so the same host must return first when the group continues its saved journey.