This update is a major milestone for The Binding of Isaac: Rebirth, allowing the community to finally bridge the gap between different PC storefronts. While the feature is currently in a testing phase, it opens up the player pool significantly, making it much easier to find synergies with friends regardless of where they bought the game.
To jump into the crossplay action, you will need to do a little bit of manual tinkering. The feature isn't toggled via an in-game menu just yet; instead, you'll need to locate your OPTIONS.INI file and modify the EosCrossplay value. Setting this value to 2 allows you to access public lobbies across both Steam and Epic Games Store. If you want the full social experience, including EGS account linking and the social overlay, you should set the value to 3.
Beyond the technical networking side, this patch also introduces some necessary quality-of-life improvements for the online experience. Text chat can sometimes get a bit rowdy in public runs, so the developers have added new moderation tools. You can now use the /mute (username) and /unmute (username) commands to manage your chat feed and keep the focus on the gameplay.
As with any beta, the team at Nicalis is looking for feedback to iron out the kinks. If you encounter desyncs, crashes, or strange item interactions while playing across platforms, be sure to report them to the official support email. This testing phase is the final hurdle before crossplay becomes a seamless, standard feature for the definitive Isaac experience.
Soren