As the Creator speaketh, JADE has a really stretchy system, and it welcomes new additions like second heads or dynamic DF-like underground lakes. The way I see it, such conceptual ideas are the best improvement since ADOM so far. That's why I'd like to see some other out-of-adom-system implemented in JADE. One idea for post though, so let it be about monster movement restrictions.

If JADE will support individual monster realization on which tiles are more preferable, we could have lots of specific monsters to kill. Imagine stone creature that can only move through stone and attacks you from wall tiles, creatures living in the water (did somebody said sharks?) or in lava only (Thomas, we've got lava, right?), huge flying creatures that are to big to fit indoors and will thus hover just outside your door, waiting. It can also give life to some extra spice in the game - like a quest to outrun some nasty brutes to the safe place, where they don't want (or can't) follow you.

Now I had some thinking on how to implement this... I am not implying that straightforward way to do this (the way ordinary monsters don't stroll through walls) is bad, but I've seen the post on these forums about monster tactics (monsters don't follow @ into the corridors, ganging up on him in rooms), and if it is going to be implemented, maybe the above suggestions can go with this one in one basket. The basket here is some simple monster AI, which favors some conditions (like having lots of allies around in the room) over the other ones (like leaving them and jumping into a volcano where immune to fire @ waits). Now don't get mad at me, I know how tedious it is to write AI, and in how buggy it gets sometimes, but consider the advantages: this way there can be elementals who'll TRY to stay in their natural habitat until lured from it by direct danger, creatures of darkness who'll TRY not to get into sunlight which'll hurt them, etc. Who said that a shark will not attempt to leap at you from the nearby river when struck by an arrow? On the other hand, it could try to hide, knowing that getting ashore wouldn't do any good.