This is a short story that I read in about 1982, and probably isn't much older. I'm fairly sure I read it in an anthology rather than a magazine, but I can't remember any other stories in the collection.
The story is set in a near-future (that is, late 20th-century) USA. A hand-held (holographic?) video game becomes very popular. The game requires the player to guide a very cute goblin character through a maze - if it reaches a dead end, it looks extremely sad and miserable. After playing the game for a short time, it becomes impossible - every path leads to a dead end, so the goblin is miserable all the time.
A government agent (or possibly an independent scientist) wonders why this impossible game is so popular, and investigates it. He discovers that (a) the game contains a telepathic device that makes the player empathize with the goblin, and (b) it's been produced by a Foreign Power to destroy the morale of America (either by making everyone depressed all the time, or just obsessively playing the game rather than working), in order to soften it up for an invasion. He's about to send his report to his superiors/the appropriate authorities, when a package is delivered to his office - it contains the game, which is already switched on, and he can't help but pick it up...
