Since I don't think I can make enough use of time flow in a small game like this, I think I'm gonna scrap day/night features and focus more on dungeons. The circle thing to the left of the HUD will either be used as:
-experience meter
-some sort of energy tank meter like in Metroid. When your energy will reach 0, the meter will drop and your energy will reset back to 50. You would find energy tanks or the like in dungeons like in Zelda or something. This is less likely to happen, though, because when you take damage/get healed it does like in Earthbound, where HP gradually increases or decreases, so healing yourself would take a friggin long time
-Level meter: The higher it is, the slower your Stamina and HP decreases. This would mean the character level is capped at 28. Also chances are big that this level gets increased via some sort of magic upgrade in shops, like in Super Star Hero.
-Hybrid of the last two
-Another idea is a level meter but everytime you get hit it decreases temporarily (and increases slowly when your stamina is capped at 50, or never and requires using a special healing item). It would then act like if when getting hit too often you actually got weaker.
As for Stamina, you basically have an unlimited amount of it and it acts like MP, but magic attacks takes a considerable amount of it, so when it reaches 0, you can't use any attack until it gets high enough. If I add dashing, running might take stamina too.
Also, like Super Star Hero, I'm aiming at having no in-game menu except the save menu. Item usage might be done via number keys like the other game or selecting item with a certain key or num keys then another key.