Level 15. Coolie Mines (2)

In the area where you found the blue key, look for a crack to your right. It will explode on its own as you approach. Enter this lava crack.

After passing the runaway drill, you will enter a corridor. Blow up the crack in this corridor to reveal some items.

Locate a crack in the ground that slightly rises upward. Check the small chamber where lava is flowing from to find a cookie.

In the section with crates and a control station before a drill, destroy the crack located behind the drill. Enter this area and navigate around to a locked chamber to find the Rail Gun.

After being propelled upward by a fan, attempt to enter the hole of another fan. Destroy the fan from its rear to exit the area.