Official source

Quick answer

[Official] Big Walk supports crossplay between Windows and Mac computer versions, PlayStation 5, and Nintendo Switch 2. If the host does not appear in an active friend-games list, use the short Join Code created for the current hosted session.

Official source

Join a friend's session

  1. Have one player host and wait until their character is loaded into the world.
  2. On the same platform service, add the host as a friend and check the active friend-games list.
  3. For cross-platform play or when the game is not listed, ask the host for the Join Code generated for that session.
  4. Enter the current Join Code. Do not reuse a code from an earlier hosted session.
  5. If joining fails, compare version numbers and make sure the first two numbers match. The third number may differ.
Official source

Find the Join Code as host

[Official] Before starting, the unique code appears in a corner of the host menu. After the session begins, open the in-game menu and choose Session Details. The Mac App Store version does not use Game Center for its friend-games list, so Mac App Store players need a Join Code.

Community report

Community-reported failure case

[Community-reported] One current Steam post describes a Steam-to-PlayStation 5 connection failure even after swapping hosts. This is a single report, not evidence that crossplay is generally unavailable and not a verified fix. Use the official connection checklist if the code is accepted but the connection fails.