With Dr. Willy presumed dead at the end of Mega Man 3 the world is at peace until the evil Dr. Cossack sends his 8 robot masters to terrorize it. Mega Man again leaps into action with his new mega buster weapon to save the day. Proto Man also makes a return to help out.
The 8 robot masters this time through include: Bright Man, Dive Man, Drill Man, Dust Man, Pharaoh Man, Ring Man, Skull Man, and Toad Man
The biggest change to Mega Man 4 is the addition of the mega buster which continues to be used in nearly every Mega Man game to date. The new arm cannon can be powered up by holding down the shoot button and allows Mega Man to fire one large shot.
Rush returns with his “Coil”, “Jet” and “Marine” configurations, but this time, the jet mode constantly flies forward once stepped on. The player can change it's altitude, but no longer has free control to fly anywhere on the screen.
Items also return with "Wire Adaptor" and a "Balloon Adaptor" which can aid the player in reaching areas not normally accessible. The adapters are hidden in stages and must be found before they can be used.
A new character was also introduced called Eddie. Eddie is a little robot Mega Man can find in levels who will throw out items for Mega Man to use.
While Mega Man 4 was also a success and considered a great game, it didn't live up to the previous two titles and is considered by many to be the turning point after which the series of NES games begin to decline.
The game is followed up by Mega Man 5
for the NES.
Mega Man 4 has been included on the Mega Man Anniversary Collection for PS2/Xbox/Gamecube.