My latest is pretty much ripped right out zelda. A maze of moving blades which stay on strict paths. I'm currently play testing my example though to make sure it's difficult yet not impossible.

Speaking of zelda and incorporating some reading I was doing in another game system, you could incorporate a kind of puzzle to any "boss" fight for added fun.

Basically, you take the four defenses i.e. AC, Ref, Fort, Wil as they are but put a patterned +/- on them. Now you can do this per hit or per round, based on the flavor you want to bring into the game. So, for this example, I'll do per round:

Round 1
+5 AC, +5 Ref, -5 Fort, +5 Wil

Round 2
+5 AC, +5 Ref, +5 Fort, -5 Wil

Round 3
-5 AC, +5 Ref, +5 Fort, +5 Wil

Round 4
+5 AC, -5 Ref, +5 Fort, +5 Wil

What this does is basically give the boss a rotating weakness, but boost its other defenses immensely. Obviously, you could use smaller mods, positive or negative, or add in to rotating weaknesses as you see fit, but generally speaking, it makes a boss fight similar to old side-scrolling action games. Maybe not something you want to do for every boss fight, but I know at my table, my players would get a kick out of figuring out the pattern and try to time their attacks appropriately.

That is an excellent idea. I like it.