Yeah, that 2008 Prince of Persia was promising and terrible. I didn't play much of it, but that feeling of having a magical string attached to you, bungee roping you back to your ledge whenever you fell, was destroying the feeling of heights and danger of Sands of Time. Not to mention that this bungee rope was actually your companion's hand, whoobviously had no problem passing all the obstacles back and forth (and catching you wherever you were, wherever needed), yet only brought you back to your starting point instead of the platform you had just missed, made it absurd in so many ways.

The proper sequels of Sands of Time were already huge disappointments (in tone, style, music). But that one... It was (ironically enough) a huge letdown.

Oh and the weekend promo reminds us of the existence of the Force Unleashed. Oh dear. Remember when we expected an update on the pretty flawless Jedi Academy ? Out with the intuitive swordfights, in with the QTE. I really don't get how, why, good games devolve like that.

I don't know if I should go with Diablo 3 or Fallout 3. Horrible, horrible, horrible games.

For me that was Half-Life 2.

A friend of mine had pre-ordered the CE. When it came it was a huge metal cookie box containing: 1 DVD in a cheap card wrapper, and a leaflet. And lots of shrink-wrapped American air (it was US imported...).

We knew it was online-DRM'd (that's why I hadn't bought it myself) and it could only be activated only day x. When the day came we installed it, which means, the Steam client which proceeded to upload all contents of the DVD to decrypt and re-download it. WTF... That took all day...

When we were finally allowed to play... the big WOW! Amazing! The whole atmosphere of City 17 was brilliant. I can't deny it. Gameplay was - well a tunnel with scripted sequences, but that was just the beginning, right? It would open to big levels to explore, with tactical battles against the Combine soldiers, right?

Well, no... the game stuck with being a tunnel shooting gallery. "Exploring" was looking into some dark tunnel which was a dead end after 5 meters and finding some jump-scare and some ammo. And let's not talk about the enemies...

I adored HL because it felt so... alive. The soldiers would search for you, try to flank you, seek cover. The aliens had different behaviour - some would actually flee, hide and wait in ambush - in different places every time you replayed the scene.
In HL2 everything seemed scripted. The Combine come at you until they drop. Throw a grenade at their feet, they don't even react to it. They never flank or retreat and regroup... And there's almost always only one way to go. In the original's On A Rail level there were many ways to approach the situation and deal with the trip-mines and checkpoints. I didn't find this in HL2 at all.

HL2 is a game I grew more and more disappointed with the longer I played. The gravity gun was a nice toy and some physics puzzles were pretty cool and it looked really great, but at the core it was a very average shooter. I quit playing somewhere after the Ravenholm level...

Ok later we still had some fun playing deathmatch with only the gravity gun allowed...

Another thing was the censorship issue. The original version was uncensored (that's why my friend bought the US version). But after a while suddenly the game was completely "bloodless". Turned out Steam had switched to "low violence"... at first that could be remedied by just setting Steam to English. But a while later even that wouldn't help - the LV version was enforced by IP range. So the expensive "original US version" was suddenly worth crap... all the while HL2 (original!) was never blacklisted in Germany AFAIK. Valve just enforced censorship for Germans without any real need... This is where much of my disregard for Steam comes from.

Already mentioned
Dragon Age 2 (a severe case of consolitis after the great Origins)
Bioshock (after all the praise, it is just a mediocre console shooter)
Torchlight (just boring)
Dragon Age: Inquisition (about 70% useless bloat and 30% actual content)

Add to that:
Mass Effect 2 (gameplay was absolutely horrid)

Good point DA2 was terrible. DA:I was better, just suffered from being a single player mmo. With a better story, and more focus it could have been much better.

Easy, Diablo 2. So much praise, ended up playing it eventually after many years of hearing/seeing that, and just hated it. And that may actually not be a too strong word. There was just... nothing there other than a pointless click fest. No characters, no story, no events or locations designed to make anything interesting, no feeling of purpose, just nothing. And the (lack of) saving and mechanics in case of dying, no thanks.

Was also very disappointed by Dink Smallwood and Larry 8, but those weren't hyped, I didn't have that many expectations, and Dink was (legally) free too.

Edit: To add some more hyped ones, System Shock 2 and Fallout 2. Nowhere like that level, but really disliked them and abandoned them before getting too far. Was a matter of specifics though, mainly the respawns and the use of the same currency for items and upgrades in SS2 and the PA setting in F2.

The Longest Journey Home and Sunless Sea, both brilliant stories packaged in gameplay poo. Don't mismatch with "The Longest Journey" which is one of the greatest stories ever told as a game.
Also I remember 100 years ago when "The Chaos Engine" Demo was on some CDROM and we loved the coop of it and we bought the full game and it was so full of DRM that it didn't WORK. No coop for you, come back one year! Back then it really hurt because games were 80Deutschmarks which are about felt 320EUR today and we had to pay it ourselves plus giving it back was simply denied by default (you opened the box, duh). Basically we were robbed by Bitmap Brothers.

Worldshift. For years I waited to get a pc strong enough to play this drop-dead gorgeous game. But when I did I remember thinking it was painfully mediocre in its execution. I'd be willing to give it another go, but it's not available anywhere online, and I have a feeling almost no-one knows about it.

You mentioned Superman 64 already, but that's my first choice. A friend and I rented it from Blockbuster shortly after it came out. We had no idea it was so bad. It only took a minute or two of playing to realize the mistake we had made. Growing up I rented tons of bad games, but I remember that night really clearly. It was immediately clear that we were dealing with a special kind of bad.

But for a more interesting answer, I'm going to say Yooka Laylee. I adored Banjo Kazooie and Tooie. Having much of the same team behind Yooka seemed like a dream come true. After a long wait and kickstarted deluxe version, I was ready to hit the ground running. It didn't take more than an hour or so to realize that it was mediocre at best. It was like they had learned nothing from nearly 20 years ago. I still 100%'d it for whatever reason. It wasn't BAD per se. Just really, really disappointing.

Since you mentioned two of the Ultima games, there's something I am wondering:
* Is Ultima 2 as bad as the games you mention?
* How about the NES port of Ultima 5 (which I suspect might actually be worse than Ultima 8 and 9)? Note that I am specifically asking about the NES port, not the other versions of the game (which are at least decent, and possibly quite good).

Anyway, back to the topic I could mention the NES Robin Hood game, due to the game lacking any form of save feature and being long enough to need it (looking on YouTube, a speedrun is about a half hour (which is around the upper end of what I consider to be a reasonable amount of time to go without saving), and a casual playthrough about triple (which is way too long).

I have never played any NES port of an Ultima game, so I can't comment on that. Ultima 2 didn't age well, that's true too and completely falls out of the canon with it's science fiction elements. And it does have far inferior graphics than Ultima 9. ;-) (but graphics and music were the only positive thing about Ultima 9 anyhow)
Ultima 5, however, was great! My first Ultima game was actually Ultima 7 and after that I played backwards through 6 to 4 and liked them all. And I loved Serpent Isle and the Ultima Underworlds. Other Origin games were great too, so the expectations for Ultima 8 and 9 were quite high and were thoroughly disappointed.

Regarding the NES/SNES ports of the Ultima games:

Short version: If you are interested in trying one, I suggest Ultima 4. It's quite different from computer versions, while managing to be a good game in its own right.

Long version:

Ultima 3: Decent version of the game, though I prefer computer versions. Gameplay is similar, with some changes to accomodate the lack of a keyboard (some new items replace the Y)ell and O)ther commands). There's a few other changes, like enemy scaling on the world map (until level 3, everything can be killed with 0 MP spells, which can be tried until they work, unlike other versions), Druids lacking their fast MP regen, and the addition of the Cold status ailment. Music is completely different from that of computer versions.

Ultima 4: Very different from computer versions, but still good. I like the changes to the battle system; of note is that there is much less RNG here (attacks usually hit, damage ranges are small) and that there's actually a reason to equip a sword in this version. Worth playing. There's also a version for the Sega Master System; that version is more faithful to the original, but still has its quirks. Music is completely different from computer versions.

Ultima 5: Bad, as I have mentioned before. They tried to remake it with the Ultima 6 engine, but I guess that was too much for the NES, and this port is basically botched. Maybe watch a speedrun if you're curious, but I would not recommend playing this version. (The fact that you said "Ultima 5, however, was great!" is a sign that you played a version other than the NES version. Anyone who's played the NES version would *not* say it was great; hence why I listed it as a disappointment; it's probably worse than Ultima 9 (which I haven't played).)

Ultima 6 (SNES): A decent version. Some stuff had to be cut, so it's not as good as the DOS version (except maybe the music) but what's there is quite faithful (more so than NES Ultima 3-5). Note that you can't control when combat starts and ends, and you can't just attack random townspeople in this version (so no killing an innocent person to take their rune). The original music is intact, and I think it sounds quite good on the SNES sound chip.

No game had ever disappointed me more than Spore. This was a life sim by Will Wright, designed to capture the entire evolution in a single game, with creature design algorithms which have never been seen before nor after, allowing you to design any creature.

And then ... they filled it with Pixar style cartoon characters, forgot to add gameplay, skipped the underwater stage, and let the first stage be (literally) ported from a smartphone app.

Tjeck this archive.org backup of the Spore fansite hookedonspore.com. That site had been active since 2006. Notice how it spikes at the release date (2008), and the just fades away:
https://web.archive.org/web/*/http://www.hookedonspore.com/

I...I thought I already posted in a thread with this exact name earlier this year.