I have played a lot of games with terrible bugs recently:
Skyrim: A character refused to talk to me, so I could not finish a main quest. I cheated to other quests, but they then broke.
Prince of Persia: The Forgotten Sands: A door refused to open, so I was unable to progress. I had to download a program that exploited another bug to get through there. It required very specific placement of my character and took hours to find the right method. Then, I died on the other side of the door, ended up back on the broken side, and had to do the whole fucking process again.
Red Dead Redemption: My character died abruptly while climbing up a hill. What the hell?
Shadow Warrior remake: I lost the ability to load saved games for the last half of chapter 12, meaning I either had to no-death speedrun that part or cheat. What a frustrating roadblock, though I did get past it.
Rise of the Triad remake: All kinds of bugs: Stairs disappearing, enemies disappearing, enemies stopping and doing nothing, floors disappearing, doors not opening, crashes, and plenty more. I had to cheat a few times because the game was preventing me from getting where I needed to go. Also, there is a weird persistent bug: If you hit the quickload button more than once before the save is loaded, the game goes into an endless loading screen.
Two Brothers: Excellent game, very imaginative, except for all the crippling bugs. Characters get stuck outside the playable area, important things disappear, you transition between scenes and end up in the wrong place, place names fail to show up after you visit them, dialogue never appears, graphics become distorted, crashes occur--the game breaks every few minutes, and since it autosaves and you cannot copy the save, playing it mean constant fear of getting into a dead end.
Bayonetta: I love this game, but I hate all the goddamned quick-time events and button mashing. Q.T.Es and button mashing are always the worst parts of games, but these ones are even worse: The instructions are usually vague, and always wrong. I never passed any of those sequences by doing what the game told me: I just mashed different buttons than the ones shown onscreen and flailed the analog sticks in different directions than indicated until I got lucky. Fuck those sequences, especially in this game.
Quest for Glory 4: I love the old Sierra games, but some of them are extremely buggy, and this is one of the worst: There are many ways to get stuck due to bad programming, and I managed to avoid most of them. Then, near the end, I thought I was safe but my character got stuck and slowed down during an action scene, preventing me from finishing.
One of my favorite games, and the best of the series is Zelda 2: The Adventures of Link. It took me years to finish, not only because it was very hard--which it was--but because the N.E.S's save functions were highly problematic, and the saved games often got erased. I love 8 and 16 bit games, but I wish they saved better.