User blog comment:Darwin-Evolution/I Need Your Help !/@comment-26200925-20150607120755

> Steam will not let me play Subnautica as it is only playable on 64-bit windows while I only have 32-bit. I mean, I've paid for it (20 €) but Steam didn't warn me or anything.

Well that's why Steam displays the requirements.

I think your post would be more useful on the official forums.