The Batman Arkham series. The series ended a while ago and the subreddit "devolved" into a giant meme, but if anyone has a serious question about something in the game they get the most helpful answers all the time.

DOTA 2 players might be the meanest. The game includes a reminder at the beginning of the match just for regular players to be nice with new players. That tells you a lot about the community (and, of course, the reminder is mostly useless). The match-accepting button gives some information and tells you the way your allies and enemies (in a single grade) normally behave, and pretty often they are in a red color that says "disruptive". It's bad. Unhinged chat and sometimes voice chat.

I played Undertale and was kind of underwhelmed. The fandom would have you thinking it was the greatest game ever made

rs, its includes ors and rs3. ors3 obsessed with gatekeeping and even annoying that affected the latter. pokemon especially its mostly not-children are the competitive part of playing the console games, game freak turned the post-switch pokemon into slop and people still try to buy it

Ooh, the weirdest goes to Helldivers 2's fanbase without a doubt. It's so fucking toxic. But I say weird and not mean because they're the friendliest bunch around as long as you don't make your opinion of the game's balance clear. But once you do... the fandom is split into two halves, and they fucking hate each other. So as to not take sides I'll explain each side from the other's view point:

On one side you have the "cry-divers", who complain about literally everything the devs do. They bitch and moan all day long about balance and how the devs' vision for the game isn't the same as theirs. The devs could give them everything they wanted but also include a tiny little nerf, and the only thing you'd hear from them is endless crying about how PvE games should never have nerfs.

On the other side, you have the "glaze-divers". They will defend the devs no matter what they do. Devs just nerfed the weakest gun in the game? Devs just blatantly lied to their community in their patch notes? Devs just shot your dog? Call the glaze divers.

Now obviously its more nuanced than this. But they sure don't know this. It's gotten so bad that someone in the first camp offered the devs an innocent challenge to demonstrate the poor balance of the game. And then someone (multiple people?) in the latter camp doxxed them, and then got them kicked out of the place they volunteer at for safety reasons because they got sent too many death threats. They might have gotten fired from their job too, but I don't remember. It's wild.

Linux?

Team Fortress 2 players are kind of the three at the same time ?

Silly and weird, fairly chill and nice overall. But the bot crisis showed an AWFUL side of this game too...

League

I play old school runescape. the community is either the nicest queer people you've ever met or absolute incels and there really not any in between.

I have at this point roughly 1.6k hours in a bunch of Monster Hunter games, though by and large the vast majority of them are in Generations and Generations Ultimate. I've never liked concerning myself with meta builds, certainly not in a cooperative PvE game that I regularly would play solo.

Now I'll preface this by saying I've made some lifelong friends in the community, one of which I traveled halfway across the US to visit a few years ago. I don't think the community is all bad, but I've found so many people who will do very little other than try to minmax DPS build via the current meta and shame others for not doing the same.

One not so bad instance I had was when I was trying to break into some higher tier armors. I was going into a fight that I figured would take a long time, knew was going to deal a decent bit of burst damage, could easily knock someone out after that burst was dealt, and most importantly had 3 people joining. Because of these factors, I went with a build where I would primarily support everyone else, then try to keep myself alive, then any time in between those priorities I would try to deal some damage. A large portion of my armor was kitted out to increase the effectiveness of my items, have them affect my teammates, make my items have chances to be reused, then I set up my inventory so I was carrying a lot of healing items and could craft more when necessary.

One of the players in that 4 man squad I remember specifically trying to shame me for bringing a lower damage weapon (chosen because it had more skill slots), having significantly lower armor rating than the others (because I only had mid game support armor, not late game), and for not dealing much damage (because I was trying to keep him and the others alive). I say this one wasn't too bad because I also remember specifically that others in that very party pointing out that although I may not have had much armor it didn't matter much since I didn't engage much and they had noticed how much I was keeping them alive which would have otherwise failed us all the mission.

The worse situation I remember was getting sent DMs about how my build was bad, I was using awful skills, I had one particular armor set that was "a trap for new players", and to "please just use [x] armor set". They didn't like I was using three skills each decided upon because they would fix reasons I kept getting combos interrupted then killed and told me none of them were necessary because "if you're in the right spots then you won't need any of those",aka "git gud". I could somewhat understand this mentality if we were in a PvP competitive setting, or if we were in a group together actively working to speedrun this monster, or if I had asked for feedback on my armor. This entire discussion came about because I was trying to share with the wider community: "hey I just found about this neat skill exclusive to this armor set!"

Smash Brothers

Find your local tournament, get accepted by them. They will teach you new tech, be super friendly and accept you as one of their own. Then one of the TO's will sexually harass and/or attempt to rape you. If it's not a TO, it's another member of the community.

Really weird and consistent shit.

I think the Ark Raider community is a little weird in so far as it is an extraction shooter, but the majority of players are opposed to PvP.

Dwarf Fortress has a community like a think tank of scientists all fucking around in game to find out new and novel ways that mechanics synergize with each other.

Unfortunately I play Rocket League... this game is ridden with bad actors. I keep the text chat on because when you encounter good faith players it's the nicest thing to be able to converse, but the price is really high. Almost constant abuse, under all its forms : racism, insults, etc. I think it's mostly unattended teenagers, but boy do they ruin stuff.

Nicest: Factorio. No matter what you build, people will applaud you for it. Someone comes in, excusing their design for neither being efficient nor pretty. "If you had fun building it, it's already great."

Worst: War Thunder. So much toxicity in the chat it's impressive. Plus a fair bit of edgy kids dabbling in racism and neo nazism. I guess that's a side effect of being Free to Play

EDIT: Downvoted by war thunder players.

Undertale's fandom makes 10x more sense when you realize it started off with the same people from the Homestuck fandom (Toby fox used to do Homestuck stuff before Undertale).

Deep Rock Galactic has a great fandom since everything about the game is about cooperating with others. Risk of Rain's fandom is also pretty chill.

Every fandom that gets popular enough will eventually become kinda toxic and have gatekeepers and people who take the game way too seriously. I wouldn't put too much stock into fanbases unless it's a multiplayer only game.

Those of us left playing Titanfall 2 are generally a pretty great bunch. Most of the people who still play actually engage with the movement system and my word, that game has aged well. I love the community; it's small enough to recognize people, but large enough to maintain an active base at all times of day. As for the meanest, definitely Rust. That community is such a cesspool. It's not even funny. Nowhere else will you find such a wretched hive of bigotry and ideological subservience. Weirdest to my mind is probably the Batman Arkham one. From what I understand they have splintered, with one side developing an internally perpetuating sort of humor that focuses on making no sense, or being intentionally absurd in some way. The other side has remained largely a normal game community, but harbor an intense hatred for the splinter cell fandom insanity.