What's the hardest game you've ever beaten?

These are the games I beat was I was young, I might never be able to beat them again.

Ghosts n Goblins (NES)

Bubble Bobble (NES)

Tetris (Gameboy)

46 y/o here. I’m pretty sure if I could play with my little brother, we could beat bubble bobble again with a little practice.
My 7 y/o son and I are working on beating Sonic 2 together right now and even though it’s on a wiimote, I picked up the reflexes and timing to get pretty competent with it.
I also beat Mario 3 with the wiimote a year ago or so. Took about a month of after dinner practice a couple nights a week.

Not sure if I can narrow it down to just one without an objective measurement of difficulty, but probably one of the following:

Mike Tyson's Punch-Out!!
Petal Crash Grand Master 1cc
Panel de Pon (Gamecube) V-Hard 1cc
Crypt of the Necrodancer - all non-Coda chars, 8:21 Cadence PB, Hard Mode clear
Puyo Puyo 20th Anniversary Challenge Battles (Hidden max level CPU and it's actually cheating, has hard drop while you're stuck playing by 1994 or 2003 rules. While the AI has some holes in it, the speed advantage is vile, especially on Fever since it's a naturally slower game mode)
Celeste (haven't done 202 but I've got a couple goldens at least)

Punch-Out is extremely satisfying to beat! Especially back when there was no internet to look up the strategies.

Elden Ring at 100% completion.

Yeah probably Elden Ring but definitely not 100% completion.
- Craziest part is that I was being paid while doing it. I was on call 8 hours daily for a client who tended to only call me for a 30 minute question. I had to sit around and wait. So I did.

Was going to say Minoria from the same guy that did Momodora, but the xp trick about halfway through lessens immensely its difficulty, and I remembered another game, Mary Skelter 2.

Mary Skelter 2 greatly revamps the difficulty, feeling like what you'd get right after beating the secret boss in the Vita / OG PC releases of Mary Skelter Nightmares. Also in the Switch version at least, there's a bug that may permanently erase abilities from one's save, and I didn't know that, which certainly doesn't help as the number of enemies increase with story progression. Also MS2's true final boss was, well, a steamroller which took me most of my healing items as the healers couldn't keep up. On the bright side, at least it served as a waking up call as I'd still play the Mary Skelter Nightmares version bundled with MS2, and some of the later bosses can be quite the challenge too (the last secret boss for me then ended up being an attrition battle).

Probably Fez — I don't beat a lot of games, as a rule. Or rather, I play a lot of games that you can't "beat" in any traditional sense. And even those that do, I tend to move on once I've mastered the mechanics, even if the game isn't "beaten".

Maybe a weird answer, but the game i had the most problems with beating it was tge very first Kingdom Hearts. I guess i just suck back then, but yes there are quite a few endboss phases that could give some people problems, but my problem was the rikku in hollow Bastion. I guess the more objective correct answers would probably be nioh.

"there's no way you're taking Kairi's heart" is burned into my brain. Also sephiroth in the colostrum.
They are simpler as an adult.

If I beat Ninja Gaiden 3: Razor's Edge that I'm playing right now it will probably be that. I know some people say Ninja Gaiden Black or Ninja Gaiden 2 (X360) are harder but Razor's Edge has felt significantly harder for me. Playing all three on Normal mode, and 3 is the only one I have no interest in trying on a harder difficulty setting in the future. Though it's partly because the game itself sucks.

Previously the title would go to the Dark Souls 3 DLCs I think. Had some huge struggles with some of those bosses there to the point where I was not having fun at all. Though maybe if I went for a magic build instead or something it would feel different. Elden Ring on the contrary felt significantly easier, but I did allow myself to use more of the tools there like Spirit Ashes. And I never played its DLC.

Cyberpunk 2077 - pre-expansion, hardest difficulty, level: Dont Fear the Reaper.

Even with a max netrunner build, took me ~100 tries, and that included the wait between attempts because it was supposed to be the secret ending.

That or anything involving Noita, unforgiving Finnish alchemic fanfiction... Im currently (4/~500), and Ive had 1 god run (died to a puddle of poly)

Probably sekiro, though I did give up at the optional fire demon at the end.

Sekiro is too intimidating for me. At least the Souls games have stuff like summons and magic and even grinding to fall back on if you feel outmatched. As far as I understand it with Sekiro you either get good enough at it or you're stuck.
- You do have a few options with subweapons and consumables, but they're limited, so you eventually have to just knuckle up and figure out what you need to be doing better in whatever you're stuck on.

Punch Out (post Mike Tyson) required the most effort. Memorizing the patterns was a real pain in the ass for me, being a kid with undiagnosed ADHD.

I don't really beat games much anymore. Most of the games I play are either open ended or don't have a defined win condition like Forza Horizon or Helldivers 2. Or they have a side story that isn't chsllenging like Tekken 8. Most have a number of things to unlock, but unlocking them isn't really beating them as they just take time.

If a game has an ending are long enough that I want to do the story the difficulty is going to be turned down a bit. If it requires a lot of remembering things I will bail out partway through because that shit is way harder for me than any kind of mechanics.

Super meat boy. Just the primary world, not the harder mirror world.

Probably a deathless run of Sekiro. Either that or my first time playing Dark Souls III before I got good at souls games. The final boss of the Elden Ring DLC before he got patched was also quite challenging, probably the hardest individual fight I’ve done but the rest of the DLC wasn’t too hard (at least compared to deathless Sekiro).

For me probably Star Craft: Broodwar. Especially when I did it on the Steam Deck. The last mission is awesome but took me a long time as a kid.

Another contender is Star Wars: Racer on the N64. For the most part the game isn't super difficult but for one race you always have to stay on this super narrow ledge. If you fall (or get pushed by other racers) you land on a part of the track that takes muuuuch longer. You're basically fucked when you fall once.

Elden Ring, Guitar Hero 2 hardest difficulty (Psychobilly Freakout took me forever).

I don't complete a lot of hard games, but those 2 stood out.

Donkey Kong Country. No idea if it holds up today, but that game kicked my butt when I was a kid.

Silver Surfer.

Didn't expect to see this one here. If you did it without cheats, you're 1 of like 10 people to beat it, congratulations. It must have taken some dedication.
Isn't that one of the games that is literally unbeatable?

I’m not good at “hard” games but the best I managed to beat was Postal 2.

Guitar Hero 3 probably? I don't play many games.

radical red, emerald kaizo, and maybe inclemant emerald. all these are pokemon rom hacks and somewhat hard. i was never able to beat pokemon insurgence elite4 on insanity mode. otherwise all were beaten at hardest available setting (non randomised)

Either Larn or TMNT for the NES