It’s hard not to point at Mega Man 4 as the game where Mega Man started to go off the rails. The game has its ups and downs, but the largest factor in its downturn in quality is the addition of the charged Mega Buster shot. There is a good game hidden beneath the surface, but it’s dragged down by some dreary design, the constant charging noise limiting the music, and a design that plays it incredibly safe. I do want to give them some credit for finally putting all the special weapons and items on a single-page inventory screen, though.
It’s hard to believe that Mega Man 4 is the first game in the series with a strict 8-boss order, but along with everything else, it doesn’t help. It’s one of several annoying traditions this game would establish for the series, along with having a set of non-Dr. Wily stages in the same format as the subsequent Dr. Wily stages (spoiler alert!). Mega Man 4 doesn’t miss with everything, though. Several stages have side paths that exist only to offer extra Energy Tanks as extra items, which I like. It also introduces two utility items to supplement the three Rush forms. It does seem like ability bloat at times (especially considering that the Rush Marine is useful exactly once in the whole game), but the idea of hiding optional items in stages rather than having them be won from bosses is a good one the series would revisit.
The weapons in Mega Man 4 are actually pretty well-designed, but it doesn’t matter because the Mega Buster is usually just as good or better. The charged shot throws off much of the balance of the game, and several enemies seem to be designed around the timing of the shot charge. The game doesn’t offer enough challenge to incentivize weapon experimentation, and you’ll find yourself switching mostly just to hit enemies that you can’t otherwise line up for a direct shot.
Mega Man 4 isn’t a bad game, and outside of the context of its two predecessors it may even be remembered fondly. Instead, it’s indicative of the the growing problems in the series and takes a lot of blame for starting that trend. It’s fine if you want more Mega Man, but there are plenty of better options to play.