Probably the best achievement I've ever accomplished in gaming was finding all secrets in Wolfenstein 3d and Doom II. It took a lot of time, but the result was sweet :) .
Thanks for the giveaway. I'd like to enter for Vampire The Masquerade - Redemption.

Not participating but wanting to share my story anyway.

I put 280 hours in Final Fantasy X, putting all the stats but luck on 255 and beating all the dark bosses except for penance. I guess that's something. =p
I completed Kingdom Hearts twice on 100% and that's about it.
Oh and finishing The Witcher 2 vanilla on normal mode. Back when it was a challenge. =P

Well, I think the speedrun trophy for Ico on Ps3.I managed to arrive at the final couch, completed the game but I miss two minutes doing all flawlessy :|
So I started a new game and this time I unlocked the trophy, but this is one of the hardest thing I did in a videogame (by the way, you must complete the whole title in under two hours: you CAN skip cutscene, but you CAN'T skip the final cutscene and ending credits, that count as time played in the stats), because basically you must play against the game and its rules, leaving Yorda behind and completing section alone, don't save at every couch because you loose time, moving during cutscenes, avoid enemies etc.

But I really like the game, is one of my favourite, and this was the final challenge, so no matter for me :)

In for Arcanum: Of Steamworks and Magick Obscura , by the way :)

My greatest game achievement?

In Medieval Total War I won a battle against much larger force (7-8 times larger). The enemy had like 1000 troops mostly infantry (not peasants, but more regular troops like spearmen and militia), some cavalry and archers.
All I could do was retreating on a small hill and let them come. They shoot their arrows and surrounded me, but my troops kept faith and I used my cavalry to destroy the routing units.

After a while I only had my general, the Varangian Guards and some 2-3 soldiers from different other units. They were so tired I couldn't pursue any routing troops. The enemy ran away for 100 meters and kept coming back until I finally won.

I also finished Pyjamarama on Spectrum.

I'm in for Arcanum. Thanks ofsaturn!

I'm in for Vampire TM: R

Best achievement in game, probably complete 100% and unlock everything of binding of isaac, after 110+ hours of game, very hard but really a lot of fun.. :D

Thanks!:)

I'm in for Divine Divinity!

Well, both of my greatest achievements was gained from two different racing games.

The ultimate was when I finished Tokyo Extreme Racer Zero (PS2). In that game you're a street racer who challenge or get challenged by other racers to "fight" on the street. The race have "life bars" where start depleting if we're behind our rival. The rivals are plenty. Counted in hundreds. Some only appears in specific time or date (according our internal PS2 clock). It was madness, but I proudly say I defeat them all.

The second one wasn't that great, but I won 6 hours race challenge in GT5.

Edit: I changed my game of choice because I just got Arcanum.

I finished Resident Evil 4 with an average accuracy rating of 99%. This was particularly time-consuming in the beginning, where I would have to reload a checkpoint if I accidentally hit a flying hatchet rather than its thrower. Missing the target even once simply wasn't acceptable. Later on I made extensive use of the Punisher (which pierces one target without affecting the accuracy rating, so I could hit both the hatchet as well as the bastard who threw it), the shotgun (pretty much guaranteed to hit something) and the rifle. The knife and hand grenades proved very useful as well, since those don't count towards accuracy either. Rocket launchers, despite their high price, were invaluable against bosses.

In for Divine Divinity since my physical copy doesn't seem to work.

I have ascended in Nethack as a wizard. It took me years. I'm not entirely sure how to convey the countless hours I have spent building up a character only to have them starve to death or get drowned by a kraken or get smashed by a drawbridge or get petrified by a cockatrice corpse or eat something poisonous before getting poison resistance or have a hallucinating pet kill them or get nibbled to death by a newt after being paralysed by a floating eye or eat one too many royal jellies while being satiated or have wands explode in the inventory after getting shocked by a monster or put a bag of tricks in a bag of holding or pick up stuff in stores with teleportitis or decide to fight a soldier ant.

Prize: Wizardry 6+7

Prize: Startopia

As for the craziest achievement I ever did: Beat Contra Hardcorps on hard with only one life

Every time I lost one life, I hit that reset button and started all over again. Eventually, I did it :P

Thanks for the giveaway, +1.
I'm in for Startopia, always wanted to try that one.
I'm counting on this quoted words big time! Answer to you question (done little less than 10 years ago):
I turned every stone and checked EVERY PIXEL inside marked area in attached map.
Become multimillionaire through thieving (and trading) and completing quests.
Time spent on achieving this is approximately 500+ hours (with additional 250 hours on expansions).

In for Divine Divinity, thanks!

--EDIT--
Congrats to the winner and thanks again ofsaturn!

The biggest thing I've ever done was to 100% Final Fantasy VI. Every character was level 99 and learned every spell from all the magicite. I also spent hours filling up all of Gau's rage abilities. It took something away from the ending though when I just used Ultima over and over.

In for Wizardry 6&7, and good luck to all the entries.

It was the year I finally not!graduated. One of the waves of a perpetual economic crisis Russia has been in for a quarter of a century hit hard, and the state decided to combat unemployment among university graduates the only way they knew: by demanding that every hopeful graduate provide a letter of intentions from a future employer or GTFO. No letter, no diploma for you, sucker! Bwahahahaha!

(And things were further complicated by hardly anyone knowing what a letter of intentions was and what it entailed, so people were fundamentally unwilling to sign it. No crappy employer would sign the letter for the hopeful graduate in particle physics with a perfect academic record, and no decent employer would promise to hire someone who technically counted as a dropout.)

People in my dorm, also unemployed and subsisting on parents' money, played WoW. What I did was glance over their shoulders occasionally and invent a couple of stupid memes on the spot, based on what I saw. LFP ouch and subs @ heroic, lol purplz. And then I hear that, along with the upgrade of the regular PvE server to Wrath of the Lich King, a new PvP server is going to open, a land of promise and opportunity, a realm (yet) untainted by packet editor and speed hacks, where everyone will be (temporarily) equal and rise in rank by their labors as befits a true socialist paradise! And to encourage people to move and grind, the first person to achieve level 80 (from 1, duh) would be gifted a set of A5 armor by the ever-generous administration!

Look, I don't really like the metagame of WoW. I love completing quests in a vaguely persistent world with other people present; their presence lends the quests meaning. And I wouldn't even think of cheating while at it. And so a new server where I wouldn't be looked upon as a feebleminded weirdo by legions of top-levels, at least temporarily, sounded appealing.

I signed up and started grinding quests, one by one, until no more remained in the starting area, regardless of their level or usefulness. I wasted quite some time dying in dungeons to monsters who noclipped through walls (because this was a private server - point of view, what's that?) One night (WoW's time matches ours), all alone in a desert, I was getting rid of a number of quests from an obscure and useless quest chain when the admin's voice thundered in the general chat. They were annoucing the list of players closest to the coveted A5 set. The one at the top was a level 40 lady, whom I knew to be a GM's test character.

The second closest, at level 33, was me.

I dropped the quests, 'ported to another continent, and started grinding XPs for realz.

Guildmates (I'm not particularly sociable, but those who are see the benefit of having a higher-level character join their ranks) offered to cook me food, to better recover HP and mana. (I refused, because the benefits from lower-level items decrease exponentially.) In real life, I subsisted on tea and noodles. I joined forces with my dorm mate and we pushed upwards together; during the day, they had to study, so I ran both characters. I met our enemy - a hunter with a pet tank - and ganked him. We would meet several times after that. The first in the world, we passed through the Dark Portal and, abusing a known bug, opened the convenient portal hub of Shattrath for our noobs. The real other world - the PvE server, which naturally started at 70 and benefitted from the previous expansion's endgame loot - supplied us with hints on broken quests that were useless to pursue and fresh exploits that hadn't yet made their way into bug reports on the word of a griefed player.

In Northrend, the third and final continent, we used a known grinding spot exploit "under the cover of day" - because the GMs, unlike me, had to go to work, the lucky bastards. Then it became risky and less profitable, and we struggled to find a new one, knowing that the enemy hunter, benefitting from the same spots and much less scrutiny, was catching up, and knowing that everyone could track our location via a hacktool map, and that every secret and trick we worked hard to uncover, because we were the first, we were trailblazers, the enemy could get for free. To lift the spirits, dressed in trash grays and quest greens, the two of us won two five-man instances and looted things we couldn't even wear, while monsters fought each other due to buggy aggro and a timely application of shadow priest magic. We took time off to help the guild to level by exploiting the aggro/party system, killing low-level mobs while XP and comparatively phat loots rained on the guildmates, safely Shielded and buffed by buggy consumables I made.

We caught wind of another grinding spot, but by the time we got there, it had been already fixed to uselessness. Wandering in the snows, I found a cave of quick-spawning spiders yet lacking dangerous venom. "Train incoming!" No-cooldown spells light up the area in holy fires, the bear swipes twenty spiders with a single paw strike, and then there are only stars of loot drops shining over a mound of corpses, and the two of us, packing everything away before the next wave. We meet the hunter again; him, 73, us, having just made 77, the characters burst in golden fire of a level-up and mow him down before the fire subsides. We "grow out of" spiders and find another place in full view of Icecrown Citadel, stupidly hard to get to because of bugged elite mobs standing guard, but the druid can now fly and ferry loot to the vendor, and nothing is a barrier for the free spirit of a dead priest.

"Hey Ever, I know you like the monastery, wanna help us farm the hat?" Sure, just wait a bit, I'll be free in a while. , really. [url=http://www.wowwiki.com/Soon#Blizzard.27s_Official_Definition_of_Soon]<i>How soon</i>, they ask. When? You'll see, I say. Just... a... couple... trains... and... you... will... see.............

MOTHERFUCKING DING.

(can we has hats?)
(No, not yet, there's still the other character.)
Aaaaaaand DING.
(ok lets farm teh hat nao guise)

There are other stories. Like that one time a friend's guild got raided by a jerk and we decided to create a character of the same class in that guild and help it skyrocket in levels just to spite that one guy, and a friend-turned-rival guild of powerlevelers decided we were out to challenge them, and we really had to challenge them so as not to lose face, because no one ever backs off like rational adults in WoW, and we shared all our secrets with them so it was a really hard time going, and my laptop nearly fried and I had to actually keep it in my lap so that it wouldn't overheat, and I composed a song about the occasion and sang it (macroed it out, really) in General, and we eventually made peace with that rival guild, on condition of me pretty please not singing that song in their presence, and then we went white-hat-but-not-really and fought real money extorters and collected evidence and faked missing evidence to get them banned, all is fair in Love and Warcraft, and we cheated our way through dozens of dungeons to dozens of achievements, ha, who cares that we failed that one time, let them think we're mortal, and then there's a sad story about how I nearly got RL-murdered, but all of that seriously pales before the golden light of level 80.

And my best non-game achievement is winning the Autumn Express, but it will have to wait until another giveaway.
Love and purplz,
--me.

We have some seriously dedicated gamers in this forum, it's impressive! I'm still reading through all the submission, and definitely looking forward to seeing new entries, but I thought I'd go ahead and add my own greatest gaming accomplishment to the tread, just for fun. This will be a long one, so here goes:

(Warning: Final Fantasy VII spoilers below!)

My 'Technically Perfect' Final Fantasy VII savegame. - A Work In Progress -

- All characters are at level 99. (When I say ALL, I mean it. *Every* character, including Yuffie, Vincent, and even Aeris)
- All characters have their Ultimate Weapons.
- All characters have their Ultimate Limit Breaks. (Learned)
- All characters have their six primary stats maxed out at 255.
- All 21 battles at Fort Condor were won. (There really are 21 battles. Most people only ever see 3-4.)
- I also read all 10 different fortunes from the Fortune Teller in The Gold Saucer, and won all unique items in the Battle Square as soon as they became available.
- All 4 Enemy Skill materia's have been Mastered.
- One copy of every materia in the game, Mastered (Except for the Underwater Materia).
- One copy of every materia in the game, with 0 AP. (Including the Underwater Materia, but excluding Enemy Skill. There are technical reasons why I do this, see below.)
- I currently have 8 sets of *each* Master Materia. That's 8 Master Magic, 8 Master Command, and 8 Master Summons. I am working on my 9th set of each, and this count does NOT include the Master Materia you can get from the 'Earth Harp' after defeating Ruby Weapon.
- 99 of every item in the game, when applicable. The max number otherwise, and all available Key Items, including the Battery and Coupons A, B and C. (This was achieved without the W-Item materia cheat, and I have 45 memory cards detailing my progress to prove it!)
- The above includes getting 99 Vagyrisk Claws on Disc 1. There is a 4.23% MAXIMUM chance of stealing just one Vagyrisk Claw from the rare Bagrisk enemy, and that chance goes down every character level after Level 11. You have a 0% (null) chance of obtaining a Vagyrisk Claw after reaching Level 78. To make matters worse, there is a 90+% chance that you will steal a useless 'Soft' from the Bagrisk instead, and each enemy will only ever have one item per battle. ~THIS WAS A NIGHTMARE~
- One Black, one Green, one Blue and three Gold Chocobos, each with max stats. (Some people thinks it's better to have 6 Gold Chocobos, but I disagree. It's much harder to max out the Green and Blue Chocobos than it is to max out the Gold breeds. I'm also planning to get rid of one of the Gold Chocobos and replace it with a carefully bred, maxed-stat Wonderful Chocobo, of opposing sex to the Black Chocobo, for breeding/technical purposes.)
- I'm on my way to maxing out my money, with a total of 3708060449 Gil. I'm hoping 9999999999 is the max, but there may be another 9 or two... To give you an idea of how insane this is, recognize that the most profitable item can be sold for only 1400000 Gil. >_< I already have the max GP (Gold Saucer currency), 10000 GP.
- All of this was done with 0 Escapes, absolutely no cheats, and most of the time I had two characters dead. (This was done for technical reasons, mostly so they would not gain any experience, see below.)

And finally, my crowning moment in video game history:

- All characters have their maximum natural HP/MP.
Words alone cannot describe the tedium and dedication it took to complete this task. To reiterate, ALL characters includes Aeris. (Meaning that I accomplished this STILL ON DISC 1, when she was alive.)
Maxing out their HP/MP involves getting a specific combination of HP/MP each time a character levels up. It may not sound so tough, but to get that *one* specific roll, you will often have to reset 50-300 (or more) times. Factor in that there are 9 characters, and that you have to do this *every* time one of them levels up (Starting around level 50) and I think you can see where I'm going; If my math holds up, that means I had to reset roughly 22,050-132,300 times. (And yet somehow it felt like so much more...)

My game timer stopped at 99:59:59 about half way through the first disc, waaaay before I even began maxing out the character's HP/MP, so I have no accurate estimate of how much time has been invested in this project. Without exaggeration, I'd say it's been no less than 400 hours, and I will have to invest at least another 400 hours to be near the completion of my Technically Perfect Final Fantasy VII savegame.... If I'm lucky. ;^)

Not in thankyou, but wanted to pass on a huge congrats for your first giveaway!
mainly not in as id end up churning out several and you want me to pick one! but great idea!