Co-op in Blind Descent is online only, for one to four players, and it runs the same campaign as solo. There is no separate mode and no separate save slot described anywhere on the store page.
- Party size: four, meaning you plus three.
- Connection: online co-op. No split-screen or local co-op is listed.
- Cross-platform: the Steam page carries the Cross-Platform Multiplayer tag. Console versions are not announced, so the tag currently describes PC storefronts.
- Solo: fully supported. The playtest ran as a solo build before the co-op build replaced it.
What a team actually shares
The base is the anchor. Because the game does not start you on an empty plot — it starts you in an abandoned research facility you clear and reclaim — every party member is working on the same structure, and the overgrowth that reclaims neglected buildings does not care who built what.
That makes division of labour the first real decision. How co-op runs covers roles, hosting and what happens when someone leaves.
Crossplay has one open question
The tag is on the store page, but "cross-platform" on a PC-only Early Access game is ambiguous: it can mean Steam against GOG against Epic, or it can be a forward-looking tag for console versions that were planned when the page was set up.
Crossplay and cross-save walks through what the tags and categories do and do not establish.