I purchased the upgrade that ways it will add one hidden room to every level. I have yet to find any of them. How do you find the hidden areas in this game?
Most of them are fairly easy to find, you need to keep a look out for a golden glow with little particles coming from it on the wall. The stone there should be crumbling a bit too. Throw a grenade or hit it with something explosive and it will blow open, allowing you inside. Feels like classic Zelda!