Deadman
DC is full of mystic superheroes. Fate, Zatanna, John Constantine, and Jason Blood, just to name a few. But these heroes are mystical because they are skilled magicians (and Jason Blood is magically bound to the demon Etrigan). What sets Deadman apart from them is: he is mystical because he is, true to his name, dead.
Deadman has all the spellcasting ability of a ham sandwich, but he can possess any living person thanks to the goddess Rama Kushna. And, Deadman uses this power to find the man who killed him.
While you can count on one hand the number of important stories that put Deadman front and center, he has a history of teaming up with other heroes and helping them in their adventures. And yes, he is good friends with Batman.
Deadman might be a second stringer in most of his adventures, but his powers lend themselves to a unique, puzzle-oriented take on superhero games. He can’t throw a punch, but the people he possesses can. The hypothetical game could ask who to possess and when.
Would Deadman possess a cop and charge into battle, risking his host’s life for a straightforward approach? Or, would he control a potential enemy, use them to perform sabotage, and watch the resulting chaos unfold?
With Deadman’s powers, developers could create a sandbox puzzle game where there’s no such thing as a wrong solution. Well, except for ones that get innocent people killed; Deadman is a hero, after all.