A while back, the 3DS Virtual Console got Mega Man: Dr. Wily's Revenge, the Blue Bomber's first Game Boy outing. It's a decent conversion of the console game, but many would agree that the handheld Mega Man games didn't really begin to shine until later in the series. Curiously, instead of working their way closer to said games, Capcom has chosen to release the original NES game first.
In case you're new to Mega Man, this is as good a place to start as any, though be warned that this first entry is quite a bit harder when compared to its sequels. It's the same deal as always — Dr. Wily has launched an evil plan and Mega Man has to defeat a group of Robot Masters in order to reach Wily's castle and stop him.
The Robot Master stages can be played in any order, and upon beating a stage you'll get that Robot Master's weapon to use in the other levels. Each weapon is another Robot Master's weakness, so if you know the cycle you can take care of all the bosses quite easily, though their stages will still be a challenge! Although the weapons you get are primarily just used to take down the other bosses, some of them have their uses elsewhere as well. For example, Ice Man's Ice Slasher can freeze enemies in their tracks, allowing you to jump on or run underneath them if you froze them in mid-air.
The Mega Man series is known for combining action with tricky platforming, but no other game in the series does this as much as the first — almost every stage has one or two difficult or annoying platforming sections that'll frustrate you to no end if you're inexperienced. Thankfully, it is possible to pick up a Magnet Beam in one of the stages that allows you to spawn temporary platforms to stand on, making any perilous section above spikes or bottomless pits much easier; this item is actually needed to beat some of the Wily stages, so be sure to grab it. If you're still having trouble, the 3DS Virtual Console's handy save state feature can also offer a solution.
If you've already played some of the later Mega Man games, you'll notice that the gameplay is still a little rough around the edges in this first instalment. The most obvious difference is that there are only six Robot Masters on offer here, unlike the eight in every other game; even the first Game Boy game had eight. Other differences are smaller, but still noticeable, like a points system that serves no purpose, temporary invincibility after being hit not protecting you from spikes, and fall speed seemingly not being capped.
The graphics are simple yet effective, most of the stages have fairly bland backgrounds (or none at all!), but they get the point across. The music is also fairly good, though some would definitely argue that Mega Man music did not truly hit its stride until the second game.
The original Mega Man was a great game in its day, but when compared to its sequels, some of which are occasionally hailed as some of the best action games of all time, it feels quite dated in this day and age. If you can look past its (comparatively) short length and slightly unpolished game mechanics there's still a pretty good game here, but if you don't like a significant challenge it might be best to wait for Mega Man 2 to hit the 3DS Virtual Console.