That sounds like base premise for GBTK (Game Breaker's Toolkit) jam made by adriendittrick.
Anyways, for worst game idea, for me it's any idea whose controls/abilities conflicts with game rule. Examples:
1. Player can only move left or right but the game requires player to move up or down.
2. Player can't control the character but it's required to complete some tasks in good manner.
3. Player is forced to read long texts to progress but the game has strict time limit.