Chex Quest came free with, you guessed it, Chex cereal. Nothing says "dichotomy of good and evil" quite like giant sentient pieces of cereal battling snot monsters.
As for Commander Keen, games 1-3 are considered to be the inferior half of the series, mostly due to not-so-good controls and a reliance on the PC speaker for sound effects. The fanmade 7-9 games get better as they go along, but also exponentially harder, especially if you're one of those people who only like to save their game in between levels.