1. OK I'm not sure what to do on this topic
2.1 Yes after an evening of thinking about this topic, I think the best solution is to add a mana bar and mana potions. The full bar would allow to cast 3~4 spells, the potion would refill the bar, and I could had mana rings that make the bar larger (say +1 spell per ring level). I think spells being overpowered is the biggest issue of the game right now, so I should do something about it for the next version.
2.3 I guess I would count 'z' turns as well as turns where you walk on cells already seen before (or something like that), so that you can't trick the game into not spawning monsters by walking around instead of waiting.
3. Yes I intend to do a different game with the pixels backend where there would be missions, and some missions would still have more than one depth; exactly as you suggest. But I need more art for that :-) I only have the terrain, items and monsters so far (no village, no tavern inside, nothing else).
4. OK I will look into it.
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Sorry I must have missed your post. I'm sorry but I can't upload the graphics version yet. As I said, I don't have the sprites for all monsters, so many late depths monsters would look the same and I believe it makes the game unplayable.