ToME: the Tales of Maj'Eyal

I got now in the Ruined Dungeon and was getting to the orbs. But the puzzle seems not solvable because one orb is inactive.

Either one of the bosses did not unlocked it after killed by me or one of the bosses got killed by one of the minions and therefore it did not unlocked the orb. Or one boss was missing in the complete dungeon.

Due this I'm not able to open the door in the orb room.

How can the dungeon get resetted or how to fix this?

I have also experienced this bug. I've seen suggestions that it is the result of a ghost or xorn guardian hiding in the walls, but I have excavated the entire level multiple times and found nothing. Checking the log also indicates that six guardians were generated, but only five ever appeared in the game. Experimentation suggests that the bug occurs prior to generation of the Ruined Dungeon, since it repeatedly occurred after a forced termination and reload.

Missing bosses seem to quite a problem sadly, one of my chars couldn't find Master, although crashing game and reloading/recreating level did the job there.

I can confirm this bug, and that bosses sometimes don't appear generally.

in 1.0.1 it still occurs. A temporary measure can be a deleting of the corresponding .teaz file from the save (first - exit the dungeon), and re-enter the dungeon. I tried to tinker that orbs' "object" file itself, but that doesn't worked.

I've seen this happen where I can't get in, but it's not because the boss is missing, but because killing the boss doesn't trigger the orb to activate. Basically, one of the guardians was either ak'gishil (sp?) or one of his animated swords. I had telepathy:all, so I saw through the wall that both already existed, and both were "unique." However, further animated swords he summoned were NOT unique. I don't know if that means the first animated sword was selected to be the guardian but couldn't exist without an ak'gishil, so one was spawned to accommodate but it got bugged, or if the ak'gishil was the guardian and didn't count for unlocking the orb because he was unique (or something else).

Just encountered this bug in 1.0.4 version. All 6 uniques were generated, but killing 1 of the uniques didn't trigger the orb. It was Xanildaeva the cold drake.

I second this. I'm not sure which guardian it was (I was playing through as an Oozemancer and destroying everything). I'm fairly certain that it didn't do something silly like teleport into the sealed room, but I can't find the bloody thing. All that loot is taunting me.

Still a bug. From reading the forums it sounds like one possible cause is a boss spawning inside the vault.

You can try adding my Bosses Gone AWOL addon. In Ruined Dungeon some of the rooms are too small for all of the bosses to spawn correctly and so they end up stuck sort of "out of phase". Even if you see six named creatures, some may be just random uniques instead of an actual guardian.