Amazing video games no one bought

In the world of video games, every now and then we'll find sleeper hits: games that fly under the radar and become huge successes, both commercially and critically. Other times, we come across games that only manage to be critical successes while performing poorly at retail. We lament these games, because not only were they awesome, but we wanted the amazing experiences they offered to spread throughout the industry. Let's pour one out for these games that were awesome, but just didn't sell like gangbusters.