Mega Man Unlimited, formerly known as Mega Man 10 before the official Mega Man 10 was released, is a standalone Mega Man fangame produced by Philippe Poulin, or MegaPhilX. Its story makes attempts to connect the classic Mega Man series and the Mega Man X series, as its Robot Masters are infected with a mysterious virus (Intended to be a prototype of the Maverick Virus) causing them to rebel against even Dr. Wily, and a prototype of Zero even makes an appearance.
The game plays similar to many official installments in the classic Mega Man franchise in terms of game feel and progression. Initially, Mega Man had only the ability to slide, like in Mega Man 3, but after complaints about the game's difficulty were raised, a patch added the ability to charge up shots to increase their power from many of the series' later installments as well. Players may battle the game's eight Robot Masters (Jet Man, Tank Man, Nail Man, Trinitro Man, Glue Man, Rainbow Man, Comet Woman, and Yo-Yo Man) and claim their weapons in any order they choose before embarking on a journey to Dr. Wily's ransacked fortress to uncover the source of the virus. Players may also explore optional side routes and collect the well-hidden Y-O-K-U letters to battle an optional ninth Robot Master, Yoku Man.
Later updates to the game would bring additional content, including a challenge mode where players can battle powered-up versions of the game's Robot Masters, an Endless Attack mode similar to that featured in Mega Man 10, a similarly-themed Endless Boss Rush mode, a tenth bonus Robot Master stage called Whirlpool Man, and a reward for players who had beaten the game: the ability to replay the game as the Z-Prototype, who consumes its own health when it attacks and regains it from destroying enemies.
In the wake of the announcement of the official Mega Man 10, this game also changed the name of one of its Robot Masters from Nitro Man to Trinitro Man, on account of the fact that a Nitro Man also existed in the official Mega Man 10.
Due to oversight on the part of the official Mega Man 10's web developers, the newsletter reporting on the game mistakenly used concept art from this game, and the official website for Mega Man 10 briefly used background elements from Comet Woman's stage as well. Though this hiccup would be quickly corrected, it led to the fangame receiving substantially more coverage than other games of its nature.