Commander Keen 2: The Earth Explodes

Commander Keen 2: The Earth Explodes is the sequel to Commander Keen: Marooned on Mars. It was developed by id Software and published by Apogee in 1990 for DOS only.

Programmed, like the other games of the franchise, by John Carmack and John Romero, it is also part of the Commander Keen trilogy, later bundled as Commander Keen: Attack of the Vorticons. The game makes use of a scrolling engine created by John Carmack called "adaptive tile refresh," which allowed - for the first time - smooth scrolling on a PC.

Commander Keen is back and ready to protect Earth from the Vorticons after getting himself off Mars in the first game. The Vorticons are looming overhead in their massive ship, just waiting to destroy Earth’s biggest cities. It’s CK’s mission to get on board the ship and take out their weapons systems. CK has to navigate the different decks on the ship, avoid the enemies and obstacles between him, and save the world. Like in the first one, CK uses his trusty raygun and pogo stick. Though many enemies are quickly dispatched with your raygun, some are not so easy to kill and are best avoided rather than faced head-on. The levels contain collectible items that reward you with points that can be used to obtain extra lives. CK must also collect key cards and other useful things to help him complete the levels.

Commander Keen 2: The Earth Explodes has the same familiar gameplay as the original, making it easy to pick up once you’ve completed the first one. The improved graphics, new enemies, and levels keep CK2 from feeling like a rehash of the original. It’s a worthy sequel and the fan favorite in the trilogy.