A classic from my childhood. A series of platform games, with colorful graphics and solid gameplay. The "complete pack" got the Vorticons Trilogy (Keen 1 to 3) and Goodbye Galaxy (Keen 4 and 5). The story of these games is simple: a young 8-year-old genius, Billy Blaze, codenamed Commander Keen, must protect Earth from any extraterrestrial threat. In Keen 1, he was exploring the planet Mars when parts of his spaceship were stolen by aliens, the Vorticons. He has to get them back. In Keen 2, the Vorticons want to destroy Earth. It's up to Billy/Keen to intervene. In Keen 3, he travels to the Vorticon Homeworld to stop them once and for all! In Keen 4, Billy/Keen goes to the planet Gnosticus IV, where he must save the Oracles, members of the High Council of Gnosticus IV, who have been kidnapped by the mysterious Shikadis. In Keen 5, Billy/Keen must confront the Shikadis, while destroying the Omeganatic, a weapon that the Shikadis built to destroy the Milky Way. For the curious, in Keen 6, Billy's babysitter, Molly, has been abducted by aliens and he must rescue her. I recommend these games for those who knew them in their youth as well as for newcomers.