What's that one Steam achievement that you're most proud of?

Armello - Cry us a River achievement (0,6%) you need to get extremely rare conditions to pull this off, but i did and made it happen, was one of the best feeling in my over 1000 hours spent in the game.

Here is an example of how you get it: https://youtu.be/m_TNR9iyz-Q

I used to be proud of the The Dark Soul (complete all achievements) from Dark Souls because it was the first "relatively" hard game I ever played. But that was 6 years ago, so many people played it over and over since then that it doesn't look impressive anymore. Probably the next best one are the Batman Arkham Origins multiplayer achievements. Mostly because the multiplayer closed down and I got them when the game had almost no players left, so I had to gather up 8 random strangers and coordinate them into a few matches, felt good being a leader for a few hours.

I hate too difficult achievements so much that I don't buy some games because of it. especially online achievements (I mean that there are single player games where they add a multi player, and in some online games everything depends too much on luck) and coop
Therefore, I have no achievements that I would be really proud of. I love it when achievements complement the game, not turn it into torture

"Hit the Spot" in OlliOlli.

I genuinely don't know, I can recall some that I really enjoyed, or was even overjoyed to get, but I don't know if I have any that I consider praise-worthy. I forget about individual achievements for most of the time.

Now I can play the game for fun

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My one is gonna be quite tame compared to others. I can't think of most achievements but I'm currently working on Catherine and getting all achievements in that will be one of my proudest. I put so much effort into it back when it was on xbox 360 that it was one of the 1st games I used a guide for. I wanted that gold on hard, i wanted all those achievements but before I could it got sold. Its been years but it will finally be complete

Dragon's dogma dark arisen speedrun achievement. A rpg which took me 100 hrs in first run was beaten in 45 minutes in third run. Had to plan in previous run like farming teleport crystals and finishing the last boss on just first battle stage (there are three boss stages last two can be skipped if one can beat the dragon in first stage alone).

first achievement i got in Hades was for petting Cerberus a million times. as soon as i saw the window pop saying "Three Headed Boy" on it i threw my head back and started to howl out the lyrics to the Neutral Milk Hotel song. it's not a hard achievement to get, it's actually probably super common by now, but the endorphin rush i got from that little surprise makes it my fave. i was just petting the freaking dog, man, i had no idea i was gonna get something so nostalgic out of it.

Avadon 2 achievement
"A Dragon's Punishment" -- optional boss that took me almost an hour to kill, there is a companion pet that is immune to the Dragon's fire attacks.

The Insane achievement from Immortal Redneck (1.9% of all players) that requires you to beat the game (all three pyramids) with 20 lives or less from start to finish. Did it on stream with 5 deaths IIRC (with beating a pyramid counting as a death). It's been a lot of fun and super tricky since my chat got rid of my weapons while fighting the last boss of the second pyramid and picked quite a few nasty scrolls that hindered my progress. If you haven't tried this game yet, I really recommend it, especially with its Twitch integration on. It'll be a troll magnet but well worth it and a lot of fun. :)

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Elite in MGSV! (Any of the endgame achievements, really)

But that might be replaced by a certain Dark Souls III achievement soon, hopefully

-DX

The ones that involve speedruns, mostly because I'm not very good at them. Gato Roboto, Little Nightmares, Agent A: A puzzle in disguise to mention a few.

No More Room in Hell

"Katniss"
Find and kill a watermelon with the Bow from 20 meters away.

Probably the last achievement I got for Glass Masquerade. It's one of my 100% games