Just played this on RM WITH. It's just an infinite dungeon crawler, but probably the most competent RPG I've downloaded. I did 3 or 4 dungeon cycles.

I don't know what the mechanic behind the bonus rooms are, but they feature a few cameos to other games to receive special accessories.
Like "The One Ring" (LotR), Thief Gloves from Locke (FF6). There was a funny recreation of mario level 1 using the green tower as a pipe, Princess Daisy gives you a belt.
I'm not sure how many more rooms there are.

But I did find a few bugs and exploits that are common to Rpg Maker.