Vampire: Bloodlines. Even with all the patches there are still some pretty major problems with the game. I can't list them all here. There's a word limit. :P But it really is still so amazing in so many ways. When you can get it working that is.

Stalker Shadow of Chernobyl. Not at all bad now. Especially with the Complete mod. But the release build was impossible to complete due to dialogue bugs that meant the main storyline was impossible to follow.

Quake 4. A similar, but smaller problem here. One single ladder was impossible to use, stopping you completing the game in the process. But this was patched out.

No one has mentionned Deadly Premonition yet? As imperfect as it may be, I really wanted to enjoy this one, but just launching it is a tricky issue.

Weird. Back in 2001, the game was virtually bug-free. Maybe the crashes originate from the way modern OS handle it?
Tannath mentionned Lure Of The Temptress, which I was unable to complete to a bug brought in by SCUMMV.

Maybe. The Desperado forum is loaded with complaints like mine.

Ooooh I had two immediately come to mind.

The first is Fallout New Vegas: the Cazador poison bug on Xbox.

I was playing in the "permadeath" mode (I forget the specifics, but companion characters COULD reach conditions where they'd be killed... for good!). I had one of my companions become poisoned by a cazador - applying a stimpak would actually ACCELERATE the rate of poison damage and anti-venom would kill them instantly (or maybe it just didn't work - I don't remember). I actually quit the game for probably 4 - 6 months before it was fixed in a patch. I remember reading the patch notes online and losing my mind when I realized they finally fixed it LOL. Unlike a less spectacular game, I actually went back and started playing again, without missing a beat.

The rebranded Sea Dogs 2 PoTC. This game was amazing, but buggy. Lots of little minor things that weren't too awful and a few MAJOR save game corruptions. My game would corrupt frequently - I took to making two saves at a time and then deleting the one that would corrupt, which seemed to work for me. Eventually I encountered a bug that broke the main quest line - I just couldn't progress the game. Lucky for me I got a ton of enjoyment out of the game up to that point, and I still love it to this day but man were those bugs a bitch.

Universe at War. My favourite RTS ever. Brilliantly designed and insanely different 3 races to play, even more radical and innovative than things like Starcraft. Made by Petroglyph, the ex-Westwood guys; they also made Grey Goo recently. Music by Frank Klepacki! The OST is free, Google it.

Had a terrible start on day 1, crashes and AI bugs everywhere. It didn't help that its campaign mode was half baked and it didn't even give you a chance to use half of the game's arsenal. Every patch made things worse, the publisher SEGA did a terrible job of releasing timely updates, and in the end they just abandoned it, and canceled the planned sequel.

With the latest patches multiplayer games work perfectly, but skirmishes are not reliable since the AI sometimes just sits there. Such a pity. To this day I still check from time to time to see whether somebody has released a fan patch or something...

Bard's Tale 3. One of my favorite games, but the IBM PC version (and from what I hear, the Amiga version) contain bugs that make the game significantly less fun.

The most significant bug is one that prevents monsters from breathing fire and prevents attacks from applying status ailments; makes combat much less interesting and the Stoneblade useless. There's also a bug involving monster locations (a certain shark enemy that is supposed to be able to instant kill appears out of the water) and another that makes outdoor dungeons dark, as well as one that makes anti-magic zones dispel light but not levitation.

Really, that particular version of the game is a mess. If at all possible, play one of the 8-bit versions instead (or wait for the remaster and hope the bugs are fixed there).

was about to mention bloodlines
that thing is a hive of bugs all working together and somehow producing a barely working game
its a great game but the issues are myriad

I played the GOG version of Blood and it wasn't so bad. The only issue I remember is difficulty level changing drastically after reloading:
http://www.gog.com/forum/blood_series/difficulty_setting_changes_when_loading_save_files/post16

Which is why I played it on Medium difficulty, which didn't suffer from this issue.

The original Shadow Warrior expansion packs had some unfinishable levels on lower difficulty settings due to the boss not appearing (and killing the boss was needed to reach the next level). There were unofficial fixes for it.

Though it was far removed from being an amazing game (especially compared to its original counterpart) Conker: Live & Reloaded had a really ugly bug in its single player that was inconsistent about whether it would actually happen or not (I understand the multiplayer had its share of bugs as well but I didn't play it).

It's been a while so the exacts of it are a bit fuzzy to me, but I remember getting absolutely frustrated when I realized I'd been through a good portion of the game and couldn't complete it. I want to say it was around the time of the Saving Private Ryan parody, where something is eventually blown up.

Instead of seeing the aftermath of whatever was supposed to actually happen in the game, I got thrown to the overworld and heard this mechanical sound effect. Nothing was around to interact with and my progress was completely halted. I thought "I'll just reload the game, that will fix it", did so and still had nothing. After a time trying to come up with any idea as to why it happened, I eventually gave up and started the game over. I was expecting the exact same thing to happen, so I was careful about how I approached the same event.

Much to my surprise, I was able to finish the rest of the game.

Even though it was lesser to the original N64 game, a bug like that should've been dealt with. I have a hard time believing no one ever encountered it in testing, so I'm left to assume that someone must've thought "screw it, we gotta ship this anyway" and left it as is.

Here's one I have read about.

In Wizardry 8, there is one part where one of your characters must consort with a demon, and that has to be a male character. In 1.0, the developers did not consider the case of an all female party, causing players to get stuck there. Fortunately, a later version made it so that, if everyone in the party is female, you could have a female character consort with the demon. (This would, of course, be a case where a lesbian couple produces an offspring, but I suppose that's preferable to getting stuck forever.)

It would be one thing if I could blame this oversight on an all-male development team, but I can't, especially with Linda Currie and Brenda Romero having important roles in the game's development.

(Also, to my understanding, Wizardry 8 1.0 had another bug that made progress on Ascension Peak impossible, making the game unwinnable for a different reason.)

(It's also worth noting that the whole "consort with a demon" part can be skipped, but only if you know about it ahead of time so you can place a portal in the right spot.)

The bug that caused 0 XP rewards for quests in The Witcher 3 was rather ruinous. Nothing more disappointing that being denied XP in a RPG. You can take away my equipment, present insurmountable challenges, but don't touch my XP!

What about RPGs without XP?

I actually do know of a similar bug in an RPG that does not use XP. In SaGa 2 (Final Fantasy Legend 2), character growth basically stops if a character gets 1024 HP or more. (Note that you can't gain HP if you already have 999, but since you can gain 20+ at a time and there's a potion that gives you 40 it's possible to surpass 1023 HP and trigger the bug.) At this point, the calculation to see if you gain HP overflows, so the game will roll that you should gain HP, realizes that you already have 999+ HP, and then stop before checking for a stat increase. For Espers (Mutants), this comes after the check to see if you learn a new ability, which uses the same formula (and is again based on HP), so you will find the character constantly learning new abilities. (Unfortunately, you can't have more than 4 Esper skills, so the last one will be constantly replaced.)

Of course, you can avoid that bug entirely if you play with a party consisting only of Robots and Monsters.

Read the title again. This thread is about good games.

LOL from what I hear thems be fightin' words ;)