Great. Just strolling along, you drop down a mine shaft to a stone-and-lave maze. Crap.

Ride the moving tile over the lava. Nearly straight ahead, there is a misaligned texture. Some light shines from it. That's a walk-through wall.

# After jumping from stone to stone over lave (and with some jerk shooting at you), you go past a sawblade in the ceiling. Right after the blade, shoot the wall with the skewed texture. Secret.

When in front the giant... frog? Lizard? Never mind. Shoot the bastard in the mouth to make it stop zapping you. Get the bars to the left opened, and shoot the wall behind them. Yeah, right. Secret again.

Further down the road, you'll pass under some long wooden beams. There is two skull pillars with a skull...something between them. Jump on top of the...something, and it opens a secret door. Inside is a teleporter which takes you up on the wooden beam.

After you got the blue key and move out of the basement, you go over another effing lava-flooded area with nails shooting up. You reach a 'V' corner with two faces across from a snake head. Jump up and headbutt the snake head, a secret door opens.