But we have been inundated with Metroidvania type Games like Axiom Verge, Hollow Knight and AM2R and others. Metroid has to stand out in some way. I think the purity of Metroid and how all the power ups are almost guaranteed usage in some (mostly pretty creative) way for progression is why the series is so strong. It's short and Punchy, 100% completion is satisfying and not hugely tedious most of the time and often has unique challenges throughout to provide consistent variety.
The thing that has always distinguished Metroid (and Zelda) for me is the elegance of a progression system based on discrete accomplishments and skill checks (discoveries, obstacles, puzzles) and almost never based on grinding or stats (though the armour upgrades in BotW stretch this a little bit). Short and punchy, as you said, but most of all
clean. You become more powerful not directly via repetition, but via the personal improvement in technical/observational skills that come with repetition. Not experience points, but
experience, in the form of actual competence as a player. And that's why I'll always find their rewards more satisfying. The power-ups feel like they individually matter in how you obtain them as well as in how you use them.
People tend to call Metroid games "Metroidvania" like they're the same thing, but really all those indies emulate Castlevania far more than Metroid. The only Metroid-likes I know of that have come out lately are Axiom Verge and AM2R.
Guacamelee! is closer to the Metroid side, but I agree: most of the time, when people pull out the word Metroidvania, I get the impression that either they have never played a Metroid game, or all they got out of the experience was that it's a side-scroller where you run-and-gun in more than one direction on a roughly contiguous map (and not always even that). You could release a Contra game these days with some minimal freedom of backtracking and connectedness between areas, and someone would call it a Metroidvania.
