A series of 2D console games by Capcom of the sidescrolling variety which are similar to the original Mega Man series, but with a darker plot and more items to find, such as various upgrade capsules and heart containers.

The games presumably take place in the future, farther into it than the Mega Man series does. It begins with an archaeologist named Dr. Cain stumbling upon the ruins of Dr. Light's laboratory. There, he finds a capsule containing a functional robot -- but a computer terminal there warns that this robot has emotions and free will, and thus would be exceedingly dangerous were it to break the First Law of Robotics.

Curious, and noting that all indicators on the capsule are green, Cain releases and activates the small, blue-armored android dubbed "Mega Man X" in the computer's files. Amazed by X's full sentience, Cain takes it upon himself to try to duplicate Light's success. Not being a true robotics engineer, he doesn't understand everything Light did, nor does he have all the resources Light does, so he has to make many approximations... but nevertheless, Cain and X successfully build a second free-willed robot, which he calls a Reploid. He goes public with his discoveries, and soon Reploids are in mass production.

However, within months, some reploids start going berserk, attacking humans with deadly intent. In response, a group of "Hunters" composed mostly of Reploids is established to keep these "Mavericks" from hurting anyone else, led by one of Cain's most advanced Reploids, Sigma. The Maverick Hunters manage to keep things under control for a few months... but then Sigma himself goes Maverick along with many of the Hunters, claiming that humans are an inferior race holding back the Reploid race.

At this point, X decides to join the sane remnants of the Maverick Hunters, now under the command of the mysterious, powerful Zero. The games chronicle X and Zero's struggle against Sigma's machinations. You can play as X or, in later games, Zero. Games in the Mega Man X series include:

According to TheBooBooKitty, Mega Man X was also available as an MSDOS CDROM.