The Tentacle Girl Game Over is an ending which occurs if the party loses a fight in the Exile Dimension.
Having been beaten, the party is quickly dragged away by tentacles into the pits below, cut off from the teleportation system that would normally save them. Separated from their friends, Eric(a) is immediately violated as the tentacles begin furiously penetrating them and unable to even scream. Initially filled with only pain and fear, in time their body is remodelled to feel only the pleasure of being used. Eventually being sufficiently transformed, she climbs out of the breeding pit once more in a new form.
It is centuries later that a pair of adventurers, one of each gender, stumbles into the Exile Dimension. They are soon beset upon by the monster that Eric(a) has become. Her face and torso are those of a girl, but in place of hands, legs, or hair are only masses of writhing tentacles. Delighted at finding new "friends" she quickly subdues the pair, her thoughts filled with plans of violating the two until they are broken.
What remains of Eric(a) is all but gone, only this tentacled horror remaining. Vaguely though she still remembers her most favoured of friends, the ones she first came here with, though their names are long forgotten. Perhaps she will go look for them after she is done with her two new friends here.