Black Widow
Black Widow hasn't gotten her solo movie yet (it's in development), but she'd be a blast to play as in a video game, maybe one that bounces back and forth between her present life as a S.H.I.E.L.D agent and her previous life as a Russian spy. Stealth would obviously be a huge factor in the gameplay (think "Tomb Raider").
Captain America
A World War II-set video game like "Call of Duty" (with less killing, obviously) but you play as Captain America? It seems like a no brainer.
Daredevil
Daredevil is a unique character in that he is blind, but his other senses are enhanced and he "sees" using radar-like vision. Scouring the streets of Hell's Kitchen in New York City, where you can toggle back and forth between a third-person point of view and first-person radar vision, would make for a new kind of superhero gaming experience.
Deadpool
The "Deadpool" movies are hugely successful, and there's no reason to think a Mature-rated game based on the character wouldn't be either. Breaking the fourth wall as Deadpool and "talking" to yourself while in combat would add extra distractions and difficulty.
Doctor Strange
Doctor Strange's magical powers would make for a fun gaming experience, and in the off time, it would be intriguing to walk around his Sanctum Sanctorum, discovering magical secrets in documents, books, and artifacts.
Fantastic Four
The Fantastic Four hasn't had success on the big screen, but maybe they need the video game treatment, where the player could potentially switch between characters — Mr. Fantastic, Invisible Woman, Human Torch, and Thing — during sci-fi space adventures.
Iron Man
Flying around in Iron Man's armor is only something average people would be able to do in a video game, and the MCU has made the character a hit with moviegoers. He could be a hit with gamers, as well.
Wolverine
An "X-Men Origins: Wolverine" video game, based on the movie of the same name, was actually received well compared to the movie in 2009. But a game based on the character, removed from any film adaptations, would provide a new, engaging storyline. "Logan" presented a Western-like film starring Wolverine, and a game could do something similar — a present-day "Red Dead Redemption."