Brainstorming Backwards Time Castle

Inspired by Dark Cloud, specifically Dark Cloud 1's endgame dungeon Gallery of Time

The Castle starts run down in the 'present', and as the player goes further into the castle, it regresses in time. Most visible in the castle itself, with shreds on the wall becoming elaborate tapestries, tatters on the floor returning to expensive carpets, less cracks in the walls, and overgrown plants receding.

As one goes back in time, the castle becomes less run down, the shreds on the floor become carpet and far less overgrowth

Dragons that go from full grown to just hatchlings, and so do other creatures

Palace Guards, probably not present in the earlier 'later' levels due to being long dead, or they're zombies and not as effective, vs. in the later levels being closer to the prime of their lives.

Golems/ Statue Enemies that don't change much combat wise, only in the later levels becoming cleaner and polished as the rigors of time haven't taken their toll

Time weapons which can either forcefully age or regress an opponent, either to render them to bones or a hatchling.

Palace Guards

Palace Guards dedicated their lives to protecting the castle. In the earlier levels, most of them are long dead or barely moving, being either zombified guards or old people who can barely move. In this state, they easily fall to either the player or other monsters roaming the castle.

In the Later levels, they're in their primes, able to charge, swing their poleaxe with great skill, and take many a hit. Bandits and Hatchlings run from them.