if it was rich in story and character development while also fleshing out some lesser known details about the universe, then hell yes. It just has to be good.

Depends on gameplay.

The pirating part of AC IV was very good.

The main story + actually assassin part of the game are kinda meh tho.

It'll share many similar elements seen on the Prime Trilogy, and what is standard on FPS games but with a Metroid twist.

As someone who wishes he'd gotten Metroid Pinball when he had the chance, yes, I most certainly would play a Metroid spinoff. I love the Metroid universe and would play any game taking place in it. Hopefully any such game would be good.

Out of curiosity, what would these similar elements be? Finding new upgrades and gradually becoming stronger as the game progresses? A far less linear structure than your average FPS? If there are upgrades, would new weapons be upgrades that you acquire and keep throughout the game, or simply things that you use and switch out like in the majority of FPSs? How much of a focus would there be on abilities outside of guns? Would boss fights be included, and if so, would they ever consist of more than "shoot it until it dies?" (i.e. how much strategy could be put into an FPS like this?)

I'm no game developer (yet) but i'll try to explain what it can be like, at least how I can imagine it.

- Definitely getting upgrades as you progress in the "campaign". New weapons/upgrades when defeating new enemies or bosses that can be equiped at a certain level (recruit-officer). A variety of plasma wepons such as pistols, rifles, smgs, snipers, and the famous arm cannon. You'll even get a Phazon Suit!

- Much more in depth exploration on breath-taking worlds, not just point and shoot. Capable of scanning objects, people, creatures, vehicles, and gaining information on them like in Prime. You are allowed to pick up dropped weapons and keeping them in the "storymode", with the option to add attatchments, ammo, ect. Those weapons you can take to the online portion of the game. You'll also pilot gunships and land vehicles and customize them if you want.

- Certain bosses/enemies require more than just shooting till it dies. You'll need strategies to defeat them. Some will require a more melee approach to accomplish a victory against them, while others might need you to use grappling whips, stuns, or bombs to conquer turn the tides on them.

- The multiplayer will probably stick with the "Traditional FPS approach", but different modes can exist. One where you do Galactic Federation vs Space Pirates, a "Search and Destroy"-esque mode, or gunship dogfights.

Hope this helps explains a bit.

A Metroid Pinball 3DS would be cool, especially in 3D!