The first Mega Man gets a bad rap due to the improvements its sequel would make, especially in the graphics department. It's far from irrelevant though as it's still fun and presents the purest Mega Man experience where the robot masters presented clear logic in weapon weaknesses and memorable levels. Despite being a series that goes decades deep, the majority of the mechanics and traits were established right at the start.
While other Mega Man games can feel like a crap shoot in what boss is weak to what weapon -- albeit it is enjoyable to experiment and discover -- Mega Man's more traditional boss characters (Fire Man, Ice Man, Elec Man) make this less of a struggle. This also helps make the levels distinct. Ice Man presents the classic snow level with slippery terrain, tricky moving platforms and the infamous disappearing blocks whose sound still triggers players' blood-pressure levels. Elec Man has a vertical level that focus on timing your way past obstacles. The rest are as varied and different, coming with their own flavor. None of these would make my list of favorite Mega Man levels, but the whole is greater than the sum of its parts. Wiley's Castle on the other hand is a real tough nut. People hate on Yellow Devil but I think he's pretty cool and fun once you get the pattern down.
The worst parts of the game come in random elements like platforms spawning in a place you can't reach or enemies spawning right on a ladder, knocking you down. While the overall product is very polished, it's in the details that the game is lacking. It is also unforgiving in its checkpoints and some of the platforming can be a real pain. It's not without its rough edges but neither is its sequel that for some reason gets a free pass in these areas from the fanbase.
The best aspect of Mega Man is the non-linearity which this entry does better than most. Some areas you can skip outright with the right use of an item -- assuming you have it. It feels great to "cheat" your way past some of the game's nastiest platforming sections. It also makes the bosses more rewarding when you happen to have the right weapon to take them out in seconds. Of course, these things are present in future entries but I found this one to have the right balance of it all alongside some great challenges and music (near the top of the series in this aspect).
I often see people say to skip right into Mega Man 2, but I don't think that one is that far removed in quality nor the series' best (though that's for another review). Definitely start here, though if you can only play one I'd recommend Mega Man 5.
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