MetaGamerScore [metagamerscore.com]
Steam Ladder [steamladder.com]
Steam Hunters [steamhunters.com]
steam-tracker [steam-tracker.com]
completionist [completionist.me]
AStats [astats.astats.nl]

My achievement hunting philosophy: I don't use autoclickers or scripts of any kind (see update below). I don't edit files/data or save scum by external means unless it's required for an achievement, and I'll do that last. I don't use cheats unless they are publicized in-game, on the game page, or in update notes, again as a last resort (I don't use the cheat menus that are in some RPGs). I don't use system time skipping. I try to actually play the games I'm hunting (until it proves it isn't worth the time) - that means no skipping VNs just to get the achievements faster (this does not apply to demos; I also spend less time exploring them in general). I also prefer to try everything myself before looking up a guide. See also Unified Achievement Hunting Rules [100pals.co] as a looser baseline.

Update: due to the high number of games that have achievements with insane clicking requirements being the primary obstacle, I will now use only the "Auto Clicker" app on Steam for such achievements (or those requiring enormous click grind for progress), and only after playing manually until it is no longer sensible.

Please note that a very large portion of my games owned, achievements, and perfects are Profile Limited and therefore not included in my Steam profile statistics. For more accurate counts, see my profiles linked above, in particular SteamHunters.

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I generally don't accept friend invites if I don't know you or why you're adding me - please leave a profile comment if that is the case.
^^^^^^^^^^^^

I'm usually invisible to avoid spamming notifications since I play a lot of idle games and games with quick achievements, so Steam might say I'm inactive. Also, Steam doesn't bother to show chat notifications, so if you send me a chat message I may not see it. I may be more responsive on other platforms.

I have lots of bundle leftovers to trade, but don't have much time for trading. Here are my profiles:
Barter [barter.vg]
Lestrade's [lestrades.com]

I don't do a great job of keeping track of my favorite games on Steam, but here are some of them in alphabetical order:
Final Fantasy XII The Zodiac Age, Groove Coaster (with caveat that it was abandoned), In Other Waters, Myst series (especially Exile and Uru), Portal 1+2, The Room series, Space Hole 2018, Spin Rhythm XD, Spyro Reignited Trilogy, The Stanley Parable, The Talos Principle, Undertale, The Witness

Honorable mention: Unpacking, and some of the games that I have written detailed reviews for.