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

I think i should say that
"Embrace the Void" From Hollow knight without a doubt,
Completing the last pantheon was something extremely insane and you could not loose even a second of focus

Definitely has to be Shapez.io the speedrun achievement of getting to level 12 within 30 minutes. For a game that I like because of planning and unrestricted builds, to be thrown into the style of speedrunning a factory builder caught me off guard but after hours of watching youtube speedruns and practice I got it as the last achievement in that game.

Wow, gratz. I heard, that mastering ranks in warframe is pain, and having last rank is insane. Well, hours demonstrate it well

Proud, huh? Well... that's a hard question.
When I think about it, do I actually feel pride at any point when achievement hunting? Or am I just ticking a checkbox because I know that I can?

I guess maybe I felt a little bit of pride when I got the last achievement in Sora. (The achievement is just named "Sora" and it's for getting all the other achievements- yeah, not very original- one of which is for beating the true final boss on "Special" Difficulty.) It is the first bullet hell game I ever 100%-ed. But, then again, I only even attempted that because I knew it's on the very easy side as far as Bullet Hell games go. Other than beating some of the bosses on Special Difficulty, which can be done in Match Mode thus skipping the stages before them, it really wasn't too difficult.

Hmm, another one that comes to mind is "Savior: Flawless!" in Wings of Vi. That one is for beating the final boss without getting hit. Only took me 525 deaths according to the ending summary. ^_^'
There is also Dustforce's only achievement- "Double S+". If I remember correctly, it's for getting an SS rank (or, however it was called) on one of the bonus levels. To unlock those, you need to get an SS rank on all the main pre-bonus levels. Those range from easy to somewhat challenging.

But, eh, now I'm just listing "hard" achievements. Others have done those before me and more can do those after me (assuming people actually still play those games...). Kinda hard to feel pride about anything when I know I'm just a drop in the Steam ocean. :X

Aztec Map Veteran from CSGO

As I got it right before it's no longer available IIRC :P

Congratulation :o)

I would say i am proud on my 100% achievement in Minion Masters because it took me a bunch of years to reach it with normal playing.
No optimization, no hardcore grinding or other stuff.

I'm going to have to say "Hardcore Player" on Titan Quest (Finish Normal difficulty with zero deaths). It's the only time I've ever succeeded in finishing an ARPG without dying at least once. I actually got about a third of the way through the Epic difficulty as well before I lost interest in the game and put it aside. I had to use a summoner build to do it, and it was touch-n-go against the final boss who kept killing my minions as fast as I could respawn them...

Spelunky 1: No gold run.

I mean, I know a lot of people have achieved this, and some streamers/YTers was doing it daily before the sequel came out, but for me, it was a exhilarating achievement. Mainly because I was convinced that it would never happen, and when it did, I was so ecstatic. :-)

Magicka has an achievement called "Hey, mach-arena!" for its Dungeons and Daemons DLC. The requirement is pretty straightforward: "Finish the chapter on hard difficulty without any player dying."

The reason I'm so proud of this particular achievement is that while I could've tried this solo, we did this in 4-player co-op. And for anyone that isn't familiar with this game, friendly fire is always on and spells from multiple players will interact with each other (usually with explosive results). There's a TON of powerful enemies throughout the level and it's real easy to get swarmed and overwhelmed quickly. It took a lot of coordination and numerous attempts, but we finally pulled it off and I'll always remember how excited we were to see the achievement pop.

I don't think I'm incredibly proud of any achievements I have so far despite being an achievement hunter. The first one that comes to mind when I think of that however would be Straight to the Core from Teleglitch, which requires you to beat the final boss in 10 seconds or less. Given that the game, which is pretty hard overall, has permadeath and the earliest checkpoint you get for that is the penultimate stage, it's a very challenging thing to do.

Another one I think of is Tactical Challenger from Vanquish. The last tactical challenge in the game is so hard it took me several hours to beat, despite the challenge itself being only around 10 minutes long.

I defeated the Hard Crystal Lich in Hammerwatch last summer. This required the skill and coordination of 5 people and that's what made this challenge so satisfying to complete. Also congrats on mastery 30 in Warframe. It took me 4760 hours to get to that point 6 weeks ago.

I'm not an achievement hunter but I think my best result was reaching level ultra in Nuclear Throne after looping the game. Still, over 11% of players achieved that so it's actually not that rare.

The other achievement would be finishing Cosmic Express without looking up answers. Although after I uninstalled the game it turned out there's some hidden constellation to solve.

There are a couple but cannot search them for now. But as an easy of telling this with a very rare achievement (0,6%), Verdun has an achievement named "Do You Even Die?" and the description is "Survive a full Frontlines match without dying.". That was a 37 minutes long match and if you ever played Verdun, you'll know how hard could it be. Being sneaky is not enough and it was 70% pure luck.

Probably 'In Mushroom We Trust' from Dead Cells. Not even 1% of the players have it and I wasn't even trying to go for it. It was quite by accident.

I don't have one that I'm inordinately proud of, but my favorite is "Need to take a dump" from Starpoint Gemini 3. I mean it's ridiculously easy to get (eject an item from your cargo hold), but just the fact that there is an achievement called "Need to take a dump".

Halo MCC

Keep Your Foot on the Pedrogas

Had to beat the whole halo reach campaign on legendary in under 3 hours.

I spent around 2-3 days just learning a lot of simple shortcuts and a couple complex ones. Did it in 2 hours and 30 mins. Thinking of doing all the other under 3 hour campigns for the rest of the halo games dunno though. Also 100% super meatboy that was hard, I played super meatboy like 10 other times before playing it on steam though so already had a couple 100 hours in the game.

For me it is an achievement from Path of Exile named "Well-Connected" (Create an item with six linked sockets using an Orb of Fusing)
It's not something very special because you can trade a 6-link item from someone else and not bother making one but to create a 6-link item this way on your own is pure RNG and for me it took many many hours and tries to get it.

100% offspring fling (Crown of ULTIMATE Motherhood achievement iirc)
I'm not usually good at difficult platformers but beating this game ia super satisfying

The "Flick or Eat" achievement from One Finger Death Punch 2. It was completely disgusting and I nearly vomited from it, but I did it, dammit.

Non, no matter how frustrating or hard it was the magic (or pride) just disappear a few minutes after completing any game.

That being said my 2 most played games on Steam Warframe (3,648 hrs on record) and Payday 2 (2,714 hrs on record) I still got a long way ahead of me to 100% both .. the problem is to me both games have lost their appeal
I'm currently pulling my legs in PD2 still 68 infamy ranks more to go, and WF -I haven't played it in over a year maybe even 2 years- I'm missing last 2 mastery ranks.

Gz on the WF completion (or soon to it), I already hit it about a month after it was available. But as expected, they keep shoveling more gear into the game with no end in sight. Watch out for the possibility that more achievements are added with content updates, and pray it's not Legendary Mastery Ranks...

Ashes to Ashes in Darkest Dungeon. To get the achievement you had to get 300 kills in endless mode and this took me 2 to 3 hours to get it. Plus endless mode had a lot of RNG so I was really lucky that day.

https://www.trueachievements.com/a216682/david-and-golyat-achievement <-- this one probably
only 2.5 % users have it on steam.
It's a hidden achievement, I wasn't trying to get it, I would not have gotten it otherwise and I was surprised when I got it. And I sent it to my friend who also had played witcher some time ago.... and he didn't get it :D So it was fun achievement even outside the game. probably my favorite.

Probably "Beginner's Luck" in XCOM2 ("Beat a mission in June or later using only Rookies). For those who haven't played the game, this basically means that you need to clear a late-game mission with a squad made up entirely of soldiers with no experience (which means no skills or special gear, minimum hit points, and lowest possible stats).

This isn't the rarest achievement I have (2%), or the most difficult one to get, but I am proud of it mostly because I earned it on my first attempt and initially thought I had failed. I chose a mission where I had to either capture or kill an enemy VIP. This meant that I didn't need to worry about actually killing any enemies with my squishy rookies that couldn't hit anything. I just needed to take care of the target and get the hell out. Things were going well. I had found the VIP, who happened to be right next to the extraction point. But when I got line of sight on the evac point, everything fell apart. There was a Gatekeeper sitting on the evac point (one of the toughest non-boss enemies in the game). It moved in and started tearing my squad apart. My rookies panicked and scattered, refusing to follow orders as they watched each other get mowed down. The Gatekeeper used an AOE attack to wipe out 2 of my soldiers, which also happened to also kill the VIP when the car he was hiding behind exploded. The enemies mopped up the rest of my troops, and the mission ended. I thought I was screwed and would have to try again, but then I saw that the main objective was counted as complete, even though the VIP was taken out by his own side. The mission was flagged as a success and the achievement popped, even though my entire squad had been wiped.

If we take into consideration the glorious Steam Monster Sale Game of 2015 i think it will be that. It was the funniest and most engaging steam sale of all times, really had good laugh with friends and the support from the community to achieve this was incredible.

Monster Summer Badge
Level 100,000,000 Monster Summer Badge. Helped the Steam Community defeat monsters during the 2015 Steam Summer Sale.

View attached image.