Ice Jam

In the third Lone Wolf gamebook, The Caverns of Kalte, Lone Wolf is sent to the frozen wastes of Kalte to apprehend Vonotar the Traitor, the renegade wizard who has fled there and now rules over the Ice Barbarians.

At a certain point in the ice fortress, you will come across a stone door which, upon examination, will turn out to be a prison cell for Loi-Kymar, an elder of the Magicians' Guild. If you walk past this door without checking it, you will find yourself at section 276... from which point on the game is unwinnable.

The odd thing is that this is a fairly big dead-end -- there are a full 30 sections to the path where you can carry on without having met Loi-Kymar, getting into combats and using your Kai powers. It's a very unusual bit of game design for Joe Dever. Whilst there are several 'conventional' deaths on this route, it is also possible to get the franchise's one and only non-fatal ending, where you put the fortress on alert and have to escape and return to your ship to report you have failed your mission.

Immediately after the prison cell, whether or not you rescued Loi-Kymar, you will be asked if you possess a Glowing Crystal you could pick up earlier in Kalte. If the wizard is with you, then he immediately gets you to throw it away before it kills you. If you are alone, then there is a high chance you will succumb to the crystal's lethal power (it can be stopped with a concentrated potion of Laumspur). It is perfectly possible to arrive at this junction without having the crystal -- but is it possible Dever originally intended the crystal to be an easier, or even mandatory, item to obtain, and so bring an end to this path, but he later changed his mind and ended up with such a big blind alley? That feels more in-keeping with Dever's style.

In any event, if you are killed by the Glowing Crystal, then you can get another slightly unusual game over:

You quickly lose consciousness. You have succumbed to the baneful power of an ancient Doomstone, a power that is deadly to all living creatures. Death is inevitable and comes quickly.

It may be of consolation to learn that your body is soon discovered by an Ice Barbarian guard, who presents it (together with the Doomstone) to Vonotar. The traitor is so elated by your death, that he orders your body to be encased in ice and displayed like a trophy in his hall. However, the radiations of the Doomstone will cause the evil wizard months of suffering and eventually bring about his own death.

Your life and your mission end here.

Which, one could argue, technically fulfils what you were sent to Kalte to do. It's just that this could surely have come at less cost to yourself.