I did the same mistake, that mistake also made me Chaotic Evil.

I will not go as far as say that the game is broken (though something like this today would have sparked an outrage, with the Souls series being an exception).

I start over, and start paying attention a bit more (I sometimes skip dialogs, I didn't see this NPC as important).

It's not a bug - it's a feature. Unless you kill Jumble. ;-)

How to break the curse:
http://www.ehow.com/how_4500537_break-reekwinds-curse-planescape-torment.html

HAHAHA!
There is a guy before the Civic Festhall, a mage in red robei think, he supposed to be a Master Of Curses, he can remove the curse I think.
But it would be better if you would reload the game and leave him alive. :)

TNO might just take the time to walk the planes in search of a cure but the artificial constraint of the narrative prevents this. The level of consequence is being determined by an external factor (like a spiteful DM), the game design.

Its like hiding a bonus heart in a level of a side scroller, and implementing a 'no backtracking' mechanic, just because. The game might be harder to enjoy now, but its a result of the design more than the players actions.

Number one rule when you can freeze save: freeze save and often!

It sure kills the mood sometimes and specifically in games like this so you sort of need to learn between saving and loading too often and losing time because you save too seldom. :)

Hey,

Sorry for bumping this. I, too, was wrathful enough to make this, in hindsight, stupid mistake.
I fixed it by downloading Near Infinity and modifying the dialog of another NPC (in my case The Onyx).
I simply added an ApplySpell(Protagonist, SPECIAL_REMOVE_JUMBLE_CURSE) command to
one of the existing dialog actions and the curse went away.

It's not like this wasn't foreshadowed in the game; the master of curses outside the Civic Festhall clearly states that since Murdersense placed the curse, only he can remove it. This is a major problem that I have with a lot of PCs in RPGs; they seem to think that since they are playing a particular role, the world should bend itself to make them more able to play that role, when in reality some decisions will always wind up making you the worse for the wear. Part of the tension from an RPG comes from those moments where you are forced to go against what your character would usually do in order to not have themselves screwed over; sure, it might be fun to play a gibbering insane barbarian causing chaos in their wake, but you can hardly expect to do so in a setting populated by vindictive mages, fiends, and gods only knows what else before you step on someone's toes, but that risk is part of the territory you have to willingly accept if you are going to RP that way. Altering the consequences of certain actions, like having a curse that ordinarily would be unremovable except by Murdersense, removes any semblance of cons between various play styles and turns the whole RP aspect of the game into glorified masturbation.

Imagine insane person took something you value. He’s totally out there, he doesn’t care if he dies, doesn’t believe you’ll actually do anything or doesn’t even understand what death means. He’s got papers for his mental problems so authorities can’t do much to him and besides the obiect he stole has little to none material value. Now, every day that guy comes to you and taunts you about that thing he’s stolen.
Will you kill him (knowing that you’ll face consequences of your deed and that you probably won’t gain anything)? Or will you rather try to trick him into giving that thing back?

Imagine in a place where there's no proper law enforcement, where death on the streets is common. Imagine someone torturing you for 24 hours a day so can't even concentrate.
Imagine telling him to stop getting him grinning as only reaction.

Will you just walk around in this unbearable state which prevents you from acting properly hoping that after a few days (if you haven't died from annoyance) you'll find a sneaky way to blackmail him (or not) or will you start beating him to make him stop ?

Wrong analogy. To correct it, let's say the ghost of your torturer will haunt you to the end of your days if you kill him. Or, to make it more realistic: his supporters will go after you wishing to take revenge for his death.
Still so eager to kill?

can someone please explain me how to do this?

1. Open Near Infinity.
2. Open PS:T in Near Infinity.
3. Find DSALABSH.DLG and go into edit mode.
4. Scroll down to Action 1 and add ApplySpell(Protagonist, SPECIAL_REMOVE_JUMBLE_CURSE).
5. Press export and save DSALBASH.DLG into your override folder.
6. Launch the game and talk to the onyx. Ask him if he is the mage who cursed the performer down the street
and the curse should go away.

Hope this helps.

Also, it is metagaming NOT to kill the NPC on the spot (before finding out that Jumble is the only person who can remove it). Casting a curse on someone is a hostile action and Jumble should logically become hostile after casting. Normally, when a random creature casts curse on you, you wouldn't think twice about killing it. Treating Jumble any differently is definitely metagaming. If you don't believe me, go cast curse on someone and see what happens. See if they go whine about it to the master of curses or kill you on the spot.

I think i have corrupted my savefile because everytime I ask him a lot of guards come to kill me and i'm not even Evil ... do you have a savefile before seeying Raven to share?

Nah, you haven't corrupted it. The guards are killing you 'cause you murdered Jumble. You have to run from them or kill them a few at a time. Thaty's what I did.

This is by far the dumbest response here. The dialogue does not afford many choices. If you are role-playing properly, it could be that your character will kill him. If you are power-gaming, you are thinking about the potential consequences. That is the opposite of role-playing.

I have good characters, who refuse to be provoked, and I have chaotic characters, who should be allowed to kill his stupid ass and use his blood to undo the curse. You see, the game designers were not creative enough in their thinking while designing this, and apparently not considering that they were creating a role-playing game with a variety of potential alignments.