whats that one level in video games that makes you regret buying it im curious

First that came to mind is the escort level in BioShock, Proving Grounds it was called. Terrible idea.

Every sewer level in existence. No exceptions.

I've never actually regretted buying a game because of one specific level or section, but in Dragon Age: Origins, I really disliked the Fade section. When I fire the game up now, I always use a 'skip the fade' mod.

Beyond 2 Souls was doing itself no favors by hopping around the timeline like a jackrabbit on meth, but the bar scene broke me. I hated that Ellen Page's character had 0 consistent characterization and her punk rock phase -a severe 180 from her wallflower persona at the birthday party- was anti-charismatic. So she wants to defy Dafoe's curfew and go out to a bar with her unseen "friends" (who never show and we can only assume are the witch-burners from the party) and I try to fail on purpose in the escape attempt, but I fail at failing. As soon as I enter the bar, I try to leave right away and Ellen overtly ignores me (No video game in history has the right to do this). As the scene rapidly progresses to a (near)rape-revenge scenario for the third "hurting terrible people" fun-time, I give up on trying to influence the story and accept the task of continuing to play until I hate it any further (I did, around the time she meets a child-soldier). After returning the cursed item to Gamestop, I discover that escaping the bar was possible AFTER the moment that I tried it. What the hell is the point of "influence the story" as a selling point if the venues for doing so are so damned obscure?! There's a slim chance I might buy Heavy Rain again on Steam, but I'd rather die than give David Cage money for anything else.

Some games have levels where the game just becomes less interesting or more tedious, but not necessarily hard; those levels tend to be long enough to overstay their welcome.

Here are some of them:

SaGa 2: Ki's Body. This is a sizeable dungeon, being the equivalent of about 8 floors IIRC (though it's a hub structure rather than linear). The enemies are the same throughout (though at least this game has more different enemy types in an area than most), and most annoyingly, there's no treasure in this dungeon, at all. This, in particular, means that robots (usually my favorite race to use) get absolutely no growth at all during this part. It doesn't help that you have to go back to the first world to go to this (mandatory) dungeon, and then climb back up past the world you were just in to continue (no teleport ability yet).

Saviors of Sapphire Wings: The dwarven fortress. This dungeon has multiple features that make it annoying:
* 12 maps, making this possibly the biggest dungeon in the game, particularly since they're close to full size. (Other dungeons with comparable numbers of maps either are not all done at once, or use less of each map.)
* It's filled with undead, and most weapons do reduced damage to undead, unless you sub-class Healer on your fighter-types.
* Speaking of sub-classing, while many characters can already sub-class, others (most notably Lumi) can't sub-class until you complete this entire monotonous dungeon.
* Making things worse, early in this dungeon, the game takes away your ability to move on the world map, so you can't revisit previous towns and dungeons if you need to pick up supplies or level anyone new.

I have some more examples of bad dungeons, particularly from the Final Fantasy series (3-6), but I'll save them for another post (in this topic).

Final Fantasy 3 (Famicom): The Cave of Shadows. Not only is this dungeon long, it's filled with enemies that split when you attack them. Because it's long, using status ailments on them (which actually *work* in this version, unlike remake versions) isn't really practical, so you just go through with a party of 2 Dark Knights (can use weapons that don't cause them to split) and 2 White Mages (yes, you do need that much healing). Also, there's lots of mandatory invisible passages to find and navigate. (In remake versions, it's a bit more interesting when I play because I have a bard who keeps singing and using Souleater instead of normal attacks works well here, making things a bit more interesting.) I should mention that running away from everything (or at all) is not a good idea, because your entire party's defense drops to 0 and enemes deal double damage on top of that; this will result in characters being one hit killed. (Having a Master store power, which would otherwise be a reasonable strategy here, also has similar drawbacks with the character's defense, making it not viable.)

Final Fantasy 4: Magnetic cave. At this point, you are already down to just one real spellcaster, and his MP is severely limited, so you can't afford to use magic much (unless you're willing to use a lot of Ethers, which may be a reasonable idea especially in 3D remakes where MP recovery gets easier later on). Furthermore, any character with any metal equipment is permanently paralyzed in this dungeon (I've had game-overs due to this). In particular, Cecil is significantly hindered here, as he's normally a sword and heavy armored fighter-type; in 2D versions you could give him a bow (for reasonable attack damage) or a staff (minor free healing every round with a healing staff), but for whatever reason, the 3D remake took away *both* of these options, meaning you now have a useless character (and you're already down one member at this point, having 4 when a full party is 5).

Final Fantasy 6: Cave to the Esper world. It doesn't seem so bad at first, but then you get to one huge floor. On this massive floor, there are only 2 enemy types in random encounters, and *both* of them are undead, so battles are extremely dull at this point. (FF5 and FF6 have too little enemy variety in any given area, but it's usually offset by having different encounters on each floor, and there's 4 enemy formations in an area, so no excuse for having only 2 enemy types between the formations.)

I could also mention the stealth sequences in Zelda: Ocarina of Time and the button mashing part of Chrono Trigger, but I've talked about them at lenght before.

I've never regretted buying a game for "that one level". Because usually "that one level" is way into the game, and I've already gotten my fun out of it.

There are of course levels I wish wouldn't exist. Like Meat Circus in Psychonauts.

hmm what was it like I cant remember?

You have to protect a vulnerable Little Sister while she is collecting ADAM. Loads of enemies, tight spaces, it takes place in a derelict museum. If you chose high difficulty, then you're in for quite the trial.
I remember BioShock as being a massive hit back in the day, the amount of reviews, articles, videos on it was staggering, media raving about Ken Levine and Irrational Games. Personally I expected something else from BioShock, but it was worth a playthrough nonetheless.

The space battles in Star Trek 25th Anniversary.

How would you say they compare to the ones in Ultima 1?

You don't have to deal with frenetic 6DOF in Ultima 1, for what that's worth, and the viewpoint is much smaller in ST25.

So even though the space battles in Ultima 1 might have problems, they're trifling compared to basically tumbling though space, "Elite" style.

too many to list... Oh wait.