Try this join order
- Connect the second controller or Remote Play input first.
- Keep player two unjoined at the main menu.
- Have player one start the game alone.
- Open the in-game cog menu.
- Select Add split screen player to bring in player two.
The order matters: connect the input first, then add the player after the solo game has started.
If “Add split screen player” is missing
Steam needs to recognize the second input. The developer also advised enabling the game’s built-in controller support before launching where necessary.
Some players have reported the menu option missing, and network errors have also been reported in solo play. This workaround will not resolve every network error.
What Remote Play Together does
The Demo has no native online co-op. Remote Play Together streams a local two-player split-screen session; it is not a separate online lobby system. See co-op modes and limits before trying a four-player setup.