>>16286
>It's not intentionally implemented into the games, though.
It damn well clearly is in all sorts of instances. Super Metroid outright demonstrates infinite bomb jumping to you in the demo movie after the first time beating it. Alternate methods of getting past ability obstacles were obviously intentional in certain parts of Super Metroid. That’s half the reason for speed booster flight and wall jumping.
For example, there's one room in Maridia where you have to reach a door that's high up, and there are all these balloon-like enemies and grapple beam blocks at the top which you’re supposed to use the grapple beam on to get up there. However, there's also this conveniently-placed straight tunnel at the bottom that's just long enough for you to charge a speed booster and fly right up to the door (and in fact, serves no other purpose). This meme that any optional non-linearity in a Metroid game was unintentional is getting rather annoying lately. And even if it were true, the fact that it is both possible and seemingly well-balanced renders developer intention moot.
So sure, you can say that all Metroid games are linear to a certain extect, in that they have a single ending and you usually have to beat all the bosses. But that is not at all what people are describing when they use the phrase "non-linear". Mostly when people talk about how non-linear a Metroid is, it isn't in the boss fights.
You need key items to progress to them. The non-linearity being that you aren't on one set path through the world. There are many ways to get to the areas and even secret ones that make it faster to get there.
How many get the Ice beam before they got the Varia Suit? Or even the Speed Booster?
How many missed the Spazer or Spring Ball?
This is what shitty "Metroid" games like Fusion are sorely lacking. This is the non-linearity that was taken away, not "Which boss should I fight first?"
"Which route should I take this time? Should I get power bombs to open up that secret passage from A to B? Or maybe I should just use the Speed Booster to take the other route?"
The complete lack of openness in Fusion's setting makes it the second-worst Metroid out there. I can't even remember the last time I fought Crocomire in Super, because the openness of the game lets me skip a large number of power-ups. In Fusion, even if you do manage to sequence break, you won't have the correct color door unlocked, or something like this will happen.
Unfortunately, the game doesn't let you do things out of order, and you don't get the plasma beam or space jump. Instead, it tells you that you've unlocked whatever the last level of doors is that you've unlocked. This does not screw up the game, however, as you can continue playing normally and come back to Nettori and Yakuza later. Bosses beaten early will always respawn until you beat them at the intended time.