I have a hard time measuring wasted potential. If we want to talk lost potential energy, then really Nintendo is the first company that comes to mind. They have a huge user base of rabid fans, desperate to have more games, but they squander their significant cushion of cash and loyalty releasing the same games with minor changes to them. I mean, they're still really good games. The new Wii U mario games are fantastic, but Nintendo for all its talent power released two mario games in the span of as many years. However, that feels like a company wasting potential, and not a game.
How about Sim City 5 as the winner? Sim games are still amazing and are great for hours of fun. Sim City 5 could have brought the system into fully rendered 3D glory, and really used the zoning system to allow a sense of running a city that's growing organically. However it turned into a huge mess, ridden with balance issues, bugs, and no one being able to play for the first couple of days.
How about Sim City 5 as the winner? Sim games are still amazing and are great for hours of fun. Sim City 5 could have brought the system into fully rendered 3D glory, and really used the zoning system to allow a sense of running a city that's growing organically. However it turned into a huge mess, ridden with balance issues, bugs, and no one being able to play for the first couple of days.