Thanks for the comments everyone.
I haven't had any opportunities to work on this recently. I can't quite remember if I was in the middle of an edit when I stopped, but I'll upload my most recent revision anyways. Assuming I didn't leave something half-finished when I stopped, this version should include:
Much lower xp requirements to level up.
A range limit, reduced mana cost and improved animation on the magic bolt.
Much faster progression of the zombie's stats (which shouldn't plateau anymore).
Smoother player movement.
Much lower protection from your starting armor (leaving plenty of room for noticable improvement).
And an improved camera angle.
ZombieSlayerV1.2.a2w
@Toamikel
SP means Stamina Points.
The grey # is your score (which increases by an amount equal to the zombie's xp whenever you get a kill).
Intelligence is the primary factor for determining the strength of all magical abilities, except for mana regeneration and perhaps the heal spell.
Using the fortify alloy spells gives the corresponding equipment stat an amount of xp equal to (2*Intelligence+Wisdom)/3. A stat requires itself^2 xp to level up. I believe Armor starts at a much higher value, thus requiring more castings to level up.
You get Wisdom xp for regenerating mana, casting heal and reviving yourself. I can't quite remember if any other spells give Wisdom xp.
There is no maximum for the stats.