Capcom’s episodic experiment Resident Evil Revelations 2 will not have offline co-op functionality on PC, much to the unhappiness of players on the Steam forum for the game.
The Steam store page for the game mentions this lack of offline co-op as a bit of an afterthought, though I suspect it’s supposed to be some kind of asterisk-style small-print disclaimer as it has a number before it. It also appears about two paragraphs down from the feature blurb advertising … offline co-op play.
Resident Evil Revelations 2 will also be launching without online co-op for Raid mode on PC, but from what I can gather this is the same situation as the console release. Capcom plans to add online co-op for Raid some time in March, after the release of the final episode (they’re doing one per week.)
Missing offline co-op is a bit of a recurring theme for the PC, which seems to still be victim of old beliefs that this platform doesn’t really “do” that sort of co-op. Even Valve used to leave it out from games like Left 4 Dead 2 (even though the code for split-screen remained and could be modded back in.) An official patch brought it back for Portal 2.
In this particular case, Capcom appears to have waited until just before release to inform people that the feature would not be present on PC. Resident Evil 6 did have PC offline co-op options, so the publisher has managed it in previous releases.