The game plays like and is heavily inspired by Mega Man, if the title screen and controls are anything to go by, but that's where the similarities end--the rest of the game looks and feels like Contra. The level design and enemy placement feel a lot like Contra, and the art style and enemy design look a lot like Contra, so I try to aim in 8 directions but can't. Aside from the Mega Man controls not working well with the Contra everything, it's just jarring in general. Let this game serve as a living reminder that Mega Man and Contra go together like strawberry jam and soy sauce.
Oh, also, bad design decision to make enemies respawn the instant their slice of screen real estate scrolls off-camera. I think you were going for "Nintendo hard" difficulty, but the enemy AI is nonexistent, so it's just tedious. NES games are "hard" because they are usually designed poorly on purpose to create artificial difficulty so the player feels like they got more content for their buck than they actually did. It's mostly cheap stuff that you can get past easily with some muscle memory and patience rather than a true challenge. IWBTG hits that nail on the head, as the game is actually very easy once you learn how to play it properly.
