I definitely agree that isolation and atmosphere with an emphasis on exploration needs to be the focus of the game. I also think it's definitely possible to spice up the gameplay to make something that's more fluid and engaging while not breaking the more meditative pace of the game. Here are a few ideas for controls/mechanics:
1. Dual analog lock-on control system with a motion option. This is just the natural evolution of the series's controls.
2. Sprinting/Speed Booster. Sprinting has been around since Super Metroid, so adding it as an option wouldn't be out of place. Sprinting doesn't have to be super fast, just a little bit more speedy as an alternate movement option. After the player picks up the speed booster, it will activate after sprinting for a little while, pulling the camera out into third person for better view and control.
3. Ledge grab. Have a ledge grab mechanic similar to Fusion/Zero Mission and other FPS's.
4. Multiple beams. Bring back the beam swapping from Metroid Prime 1-2, and be really creative with it.
5. Melee attack. This could be a simple bash with the arm cannon or her fist that leaves enemies stunned for a little bit. Basically, it would be the attack from Samus Returns in first person. Perhaps Samus could even charge it up with energy or something similar to make it more powerful.
6. Grapple beam pull. You can latch on to certain enemies. Humanoid or medium-size enemies would work well. After latching on, Samus can pull the enemy towards herself and then either attack it with a melee blow or, if there is a fully charged shot, fire it at point-blank range for an attack with extra damage. If it's a large enemy, maybe Samus could pull herself in for an attack and then either get pushed back or jump back to her original position to resume normal combat.
7. Dodging mechanic. Have a button that allows Samus to boost quickly in the inputted direction, similar to how she was able to strafe in the original Prime series, but quicker and not tied to jumping side to side. It might feel better and more effective if it pulled out into third person. However, pulling out into third person might break the flow of combat.
I think these options can help to modernize the combat and movement without making the game too much like FPS's, especially if the focus of the game is still isolation, atmosphere, and exploration. Since the objective is not just to get to the end of a level, sprinting around as fast as you can isn't always going to be the best and most desirable option, but it would be an option nonetheless. The added combat features can help to make combat more exciting and varied while still keeping that from being the focus. Along with these gameplay improvements, I think that some visual cues and improvements, such as varied melee attack animations, more animation steps on dodging or jumping in order to make it feel better, and details such as the visor flashing red and/or shaking after a powerful attack has hit Samus, can really help to make things a bit more exciting, creating a bigger contrast between the adrenaline-rushing combat and the more meditative exploration, emphasizing both. As long as the eerie atmosphere, music, exploration, and designs remain the focus throughout all of it, I think things like this will help to add more elements to and spice up the gameplay we all know and love.
