Thanks for playing it, and the kind words.
I'll definitely tweak the movement next time I make a turn based dungeon crawler/ if I work on this more after the jam.
RE: Leveling up Light Vs. Dark, they do what they say on the level up screen. Light gives defensive stats (parry mitigation, rest hp recovery, more raw hp) and Dark gives offensive stats (Base damage, bonus damage when hitting opposite element.) Going pure dark, its possible to one shot light enemies and two shot dark. Going pure light, you can get to a point where resting in combat heals more damage than enemies do in a turn. It still ends up being optimal to keep the two fairly close to each other though.
The other consideration is what you need more in the moment, if you level up with a bunch of dark type enemies around you, it might make more sense to choose light and vice versa.