Commander Keen 2: The Earth Explodes is the second game in the first trilogy of Commander Keen platform games, called Commander Keen: Invasion of the Vorticons. In this episode a Vorticon Mothership is poised above Earth, preparing to destroy the planet with their deadly Tantalus Rays! Commander Keen's mission is to stop these evil Vorticons from blowing up the Earth. In order to do this you need to find and destroy each X-14 Tantalus Ray, powered by cells from the big purple Space Amoeba.
The game begins with a top-down map of the mothership. This is the level select screen, where you can walk around and choose the next level you want to enter. On each level, you have to find the exit; if this is one of the levels with a Tantalus Ray, you've got to destroy the Ray before exiting. Once you reach the exit, you're back on the map of the mothership.
The levels are typically full of enemy creatures and hazards. If Keen gets shot or touched, or falls into a pit or hazard, he dies, and you're booted out of the level back to the overhead map and lose one life.
Thankfully, Keen can defeat some of the enemies with his raygun. He also has a pogo stick which allows him to jump very high. Other items to find include keycards that open locked doors and bonus items which give score (Keen gets an extra life if he collects enough score).
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