A large number of gaming subreddits - including the huge /r/gaming discussion board - have removed user access and set themselves to private, effectively shutting themselves down.
Other high-profile gaming subreddits to go dark include /r/GTAV, BioShock, ClashOfClans and Elite Dangerous.
The downtime is part of protest affecting hundreds of subreddits - including some of the site's biggest - that follows the firing of a Reddit moderator by the company's top brass.
Reddit mod chooter, real name Victoria, was a key staff member for the site's popular /r/IAmA board - "I'm X, ask me anything" - which regularly allows Reddit users to quiz celebrity guests, people with interesting or high-profile jobs, or just those who have had notable experiences to share.
Chooter was fired shortly after a controversial Reddit AMA with US civil rights activist Jesse Jackson, although reports differ over whether this was the direct cause.
The mod had also expressed her dislike at the rise in AMAs for commercial reasons - for example with actors promoting a new film. Her posting history for the past 48 hours has now been deleted.
The subreddits for Books, Science, Music, History, Art, Videos, Today I Learned, Ask Reddit, Gadgets and Jokes are all now private, among hundreds of others.
Reddit's management has yet to respond to the situation.