Cuphead (2017)

Two local players share the same demanding boss fight, and a quick parry on a partner's rising ghost can bring them back. That rescue creates a real reason to watch each other rather than race for damage. This is chiefly a boss-focused run-and-gun, with separate platforming stages between fights. Pick it for siblings who enjoy learning a pattern together; both still need to dodge and aim, and a rescue becomes risky when the screen fills.