I'll maily write about it in my blog so if you're curious to know how it's progressing, just read it.
How do we access your blog? I see no link on your main webpage.
If the primary combat setting is going to be in a Tower, I think each level or floors should have unique goal(s) that the player must accomplish to move the story forward and to access the next level or floor of the tower.
For example: Floor One
Required: Find key to access next floor of tower.
Required: Locate trapped prisoner.
Optional: Find treasure chest.
I think you should add 50 enemies and then have five variations of them.
For example:
(1) Ghost: Every other attack player misses.
(2) Creepy Ghost: 25% chance to instill fear in player.
(3) High Ghost: Chilling touch freezes player.
(4) Mystical Ghost: May summon two random Ghost of any kind.
(5) Elite Ghost: Invincible to magic based attacks.
I think exploration, to some degree is necessary, for each level to provide something other than combat.
I think objectives based on an interwining story would keep the game exciting and motivate the player to keep continuing, rather than motonous gameplay whereby all we do is fight, pick up items, equip, move onto next level, fight, rinse and repeat.
Turn-based combat would be my preference and varying difficulties.
The Tower should be atleast twenty levels deep if not more.
Think of FastCrawl with more substance!