A pioneering 2D platformer that still holds its own today against classic like Super Mario Brothers 3 and Alien Hominid.
You are eight year old Billy Blaze, a young genius who has constructed a rocket in his backyard (The Bean-with-Bacon Megarocket). When the sitter falls asleep, the parents go out, or Blaze is otherwise left to his own devices, he become Commander Keen. The fourth game in the series made the leap to support EGA and VGA resolutions (640x480 and 16 colors).
Keen is a standard 2D platformer with slanted 3D visuals, similar to Contra for the NES. Keen can run, jump, pogo, and super-pogo, as well as fire his stun-gun up, down, backward and forward. Enemies hit make goofy faces and have stars around their heads. This game does not take itself seriously.
The goal of the game is to stop the Shikadi - a race of energy beings - from completing the Omegamatic, a doom machine. In Episode IV he travels to Gnosticus IV to learn about the Shikadi, only to find the Oracles have been kidnapped and scattered across the lands. As Commander Keen you must traverse the various levels, avoiding obstacles, enemies and gathering keys to help you pass doors. There are a significant number of hidden bonuses in the form of false walls or invisible platforms, that make the game both replayable and fun to explore.
Graphics: The level designs are great. It can be challenging without being frustrating. Keen and enemies are animated well, are colorful, and unique. The backgrounds and elements are fun to look at, and mesh well with their population.
Sound: Audio is okay, at best. The sound of Keen's gun is a mild bleep, and whenever you hit an action key such as jumping there is a boop noise. The soundtrack is pure midi loops, but is more ambient than annoying, which is good.
Gameplay: Keen is just fun in the tradition of Super Mario Brothers. It is a side-scroller that is entertaining and well-paced. There are numerous in-game jokes that lighten the atmosphere. If you enjoy 2D sidescrollers, and finding yourself smiling during a game despite yourself, it's likely you'll really enjoy Keen.