max of 3 players
players can set their games to 3 session types:
Friends only and public will make your game session show up in the session browser (only for your friends if set so of course) and anyone who can see it may join at any time
after a player has joined, they will be put into spectator mode until either the session host dies or manually interacts with a world stone, after which all currently spectating players will respawn.
There is friendly fire in the game, but you cannot hit a weakspot on other players for increased damage or damage them with melee