Walk through blocked doors

This glitch can be exploited to walk through any blocked door or obstacle in the game. Unequip any weapon you have so that your character uses only the punching and kicking attack. find a blocked door and place your character so its back is against the wall and its frontside is facing another wall so that he cannot move forward, now use the unequiped characters 3 stage attack
When the character finishes the 3 stage combo he moves backwards a short distance , even if your characters back was completly parallel against the wall , keep using the 3 stage combo and eventually you will have completly made your way through the door

Note: This trick is hardest to pull off on the forest stage

Note 2: The trick can also be used to avoid all the back tracking needed to unlock the ruins stage