How can anyone trademark Edge in a video game?

Circuit’s Edge is a computer game developed by Westwood Studios and released by Infocom in 1989. It was based on George Alec Effinger’s 1987 novel When Gravity Fails. The game was a hybrid interactive fiction/role-playing game; it contained a window of text, a graphic window for depiction of the player’s current location, and various menus and mini-windows for character statistics and other game functions.

Planet’s Edge is a 1991 space science fiction computer role-playing game developed by New World Computing with Neal Hallford as the lead designer. The game’s plot centers on investigating the sudden disappearance of planet Earth, by venturing out into the universe from a moon base. There are two main play modes: real-time exploration and combat using various spacecraft, and turn-based exploration, problem solving, and combat on the surface of hundreds of planets. Like most CRPGs, the game features a variety of objects, weapons, and quests/missions, but unlike most CRPGs, it lacks any detailed experience or stats system for the four characters the player controls.