Commander Keen in Invasion of the Vorticons

Commander Keen in Invasion of the Vorticons is a three-part episodic platform game developed by Ideas from the Deep (a precursor to id Software) and published by Apogee Software for MS-DOS.

Episode One: Marooned on Mars
In the first episode, the eight-year-old child genius Billy Blaze builds a spaceship and puts on his older brother's football helmet to become Commander Keen. One night while his parents are out of the house, he flies to Mars to explore, but while away from the ship the Vorticons steal four vital components and hide them in Martian cities. Keen journeys through Martian cities and outposts to find the components, despite the efforts of Martians and robots to stop him. After securing the final component, which is guarded by a Vorticon, Keen returns to Earth—discovering a Vorticon mothership in orbit—and beats his parents home, who discover that he now has a pet Yorp.

Episode Two: The Earth Explodes
In the second episode, the Vorticon mothership has locked its X-14 Tantalus Ray cannons on eight of Earth's landmarks, and Keen journeys to the ship to find and deactivate each of the cannons. Keen does so by fighting more varied enemies and hazards and a Vorticon at each cannon's control. At the end of the episode, he discovers that the Vorticons are being mind-controlled by the mysterious Grand Intellect, who is actually behind the attack on Earth.

Episode Three: Keen Must Die!
In the third episode, Keen journeys to the Vorticon homeworld of Vorticon VI to find the Grand Intellect. He travels through Vorticon cities and outposts to gain access to the Grand Intellect's lair, fighting mostly against the Vorticons themselves. Upon reaching the lair, he discovers that the Grand Intellect is actually his school rival Mortimer McMire, whose IQ is "a single point higher" than Keen's. Keen defeats Mortimer and his "Mangling Machine" and frees the Vorticons; the Vorticon king and "the other Vorticons you haven't slaughtered" then award him a medal for saving them.

Why It Rocks

 * 1) It showed the true potential of IBM PC's and compatibles.
 * 2) The games featured very smooth scrolling, which was thought to be impossible on IBM Computers of the time (See: mh:crappygames:Super Mario Bros. Special).
 * 3) The gameplay is great and addictive.
 * 4) Simple, but nice sound effects.
 * 5) Well drawn and cute Graphics.
 * 6) Nicely designed levels, sometimes similar to Super Mario Bros., minus the ? blocks and pipes.
 * 7) The pogo stick makes you jump higher (if you hold the jump button), and also acts like an autojump function.
 * 8) Lots of collectibles, like keycards, laserguns, lollipops, candy bars and burgers.
 * 9) While the plot is not important, it's still a nice addition.
 * 10) There are even secret levels, just like in any other id Software games.

Bad Qualities

 * 1) The episodes get progressively more difficult, with episode 3 considered the hardest.
 * 2) Firing the raygun requires you to press Ctrl and Alt simultaneously, and the buttons by themselves are used for jumping and using the pogo, respectively.  This can often make higher jumps difficult, and the player might inadvertently fire the raygun.  This was addressed in Goodbye, Galaxy! onwards, where firing is mapped to the spacebar.
 * 3) No music, and sound effects are only provided by the PC Speaker.
 * 4) Episode two lacks any secret levels, and feels little more than a stopgap.
 * 5) Only one real boss fight, at the end of episode 3.

Trivia

 * It originally meant to be a port of Super Mario Bros. 3 for the IBM PC. However, Nintendo didn't want to sell games for other platforms, so developers made Commander Keen instead.
 * Keen appears in a lot of id Software games as an easter egg.

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