• Increase range on missiles (i.e. arrows, magic bolts).  They should be able to be fired well out of the screen's range.
• Art for missiles hitting objects or walls, instead of just instantly disappearing
• When an enemy is activated, or becomes awake and starts chasing you, all other enemies in a proximity range should be awoken as well.
• Add better pathfinding, look into "A Star" algorithms.  (This should be lower priority, it's honestly not bad for the most part.)
• Starting out is a little difficult, I realize it's a demo though.

Great work, I can tell you've poured your time into this.  I'll stop by more later.

Peace.