Happened to me with a five-headed hydra. However it seemed to get to it senses after a while.

Does it happen in JADE 0.1.2? So far I fail to reproduce the problem...

This bug still happens in 0.1.2.

yep, happens in 0.1.2 and lets you kill the same monster multiple times

I have experienced this, but it doesn't seem to happen every single time...

A goblin scavenger followed me upstairs. I attacked him immediately, striking and killing him in one hit. He didn't disappear immediately. I stood on the spot (pressed '5') repeatedly, and he remained for another 29 turns before disappearing.

Next I lead an orcish warrior upstairs with me. I attacked him immediately, but missed him. He didn't attack back immediately (maybe just slower than me, but probably 'frozen'). I moved away one square and he remained in the same spot. I moved back next to him and pressed '5' repeatedly. After a total of 27 turns since I attacked him, he finally responded and began attacking me. His behaviour from then on seemed normal. We exchanged blows and when I killed him he disappeared immediately (as normal).

Strangely though, I lead a giant rat upstairs, attacked it and killed it in one hit, and it disappeared immediately without any of the above weirdness... Very strange! :)

Edit: This is in JADE 0.1.2

Also, I just noticed something else:

I lured 2 goblins upstairs and instead of attacking them immediately, I walked away from them. I took 3 steps before they began doing anything. Me speed is only 90, so I doubt that's the reason. Possibly related to this?

Yes I had the same problem in 1.2 two goblins followed me up the stairs and I killed them each like 10 times... racked up the xp... and didn't even feel guilty...

Regarding the "you can kill them repeatedly" part, I just had an interesting idea.

How about a special kind of cat, and you can kill it up to nine times (the exact number would be set on generation of the cat). Obviously, it wouldn't be totally still in the process, but perhaps each death could require an extra "turn" before it reanimates.

It would serve as a kind of tribute to this funny error.

Fixed for JADE 0.1.3. Please send your real name to creator(at)ancientdomainsofmystery.com for it to be included in the credits.