These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Blaster Master
Adaptation Displacement: When the PS1 sequel Blaster Master: Blasting Again was released in Japan, instead of following the original Metafight plot (see below), it actually followed the plot of the American version.
Americans Love Blaster Master: Metafight is not particularly well-remembered in Japan, probably due to the somewhat non-linear action-based gameplay. For the same reason, Blaster Master is beloved by gamers who cut their teeth in the NES era, as the game practically out-Metroided the original Metroid. The awesome tunes helped this.
This is so fantastically prominent that while Metafight practically fell by the wayside, America got a UK-developed exclusive sequel, a novelization, inspired several Game Boy ports, and by the time the Blasting Again rolled around, the American plotline superceded the Japanese one, even in Japan. And the game got a re-release on the Virtual Console due to, you guessed it, American pressure.
Anti-Climax Boss: Enemy Below's third boss. Considering he was fairly hard in the first game... Here, he's a complete joke and can be dispatched without him getting a single hit against you.
The UK version goes even further, pausing can prevent death Jason failing, getting trapped in a wall now shoots your upwards and combining these two with the door glitch allows you to complete the game without fighting the first seven bosses and leaving SOPHIA at the start of the game.
Macekre/Woolseyism: The Famicom version, Chō Wakusei Senki (Super Planetary War Chronicle) Metafight had a pretty standard space opera plot and setting. The game was set in the distant future on an alien planet and instead of a young boy looking for his missing frog, the main character was a space soldier sent to destroy an alien overlord. However, most of the plot is detailed only in the manual and only the opening and ending are actually different.
Player Punch: The seventh boss battle, if one reads the aforementioned Scholastic Publishing tie-in, becomes one, as it turns out that the boss is Jason's escaped pet frog, Fred.
But when you beat the game, you see Jason and Fred sitting on SOPHIA's roof watching the enemy's stronghold crumble, so either Fred turned back to normal after being defeated and the game never bothered to show it or neither of the frog bosses was Fred and Jason found him somewhere between beating the final boss and escaping the enemy stronghold.
The Worlds of Power novelization explains that the frog boss' appearance was merely a disguise, meant to torment Jason psychologically. The real Fred was alive and well.
That One Boss: In the first game, the sixth and seventh bosses. Not to mention the fifth boss if you didn't enter his room with your gun fully powered-up.