Put down your web-shooters and retract your claws: “Marvel Snap,” a popular mobile card battler game in which players assemble teams of superheroes to fight each other, went dark this weekend.

Don’t blame Thanos: “Marvel Snap” is a casualty of the U.S. government’s move to ban TikTok over fears about its parent company’s Chinese ties. It’s not just TikTok that winked offline ...