I don’t play board games solo, but here would be my recommendations of games that I have played with two players, but are also possible to play solo:

• Sherlock Holmes Consulting Detectives: It is mainly reading and coming up with theories, but I really enjoy it. I played the brown and latest green box. I recommend to start with the green box.
• Gloomhaven: I played the original Gloomhaven, but for starters I think the Jaws of the Lion box is a much better starting point.
• Gaia Project: You can play the with the Automa cards, it can be pretty challenging!

Blood on the Clocktower, but you kinda want 8 to 12 players for that.

You can find the top 50 largest subreddits by amount of subscribers here: https://subredditstats.com/list/most-subscribers

Compare it to the list of https://reddark.untone.uk/ and you can see that not all the largest subreddits are listed, for example r/AskReddit.

In march 2023 there were 3,125,000 subreddits. So the total % of subreddits going dark is very low. However I assume a lot of subreddits are very small. It would be interesting to see how many of the top 1,000 or 10,000 subreddits are in private mode right now. source for total amount of subreddits: https://backlinko.com/reddit-users