Duke Nukem Forever (50% Off)
Price: $9.99 (50% Off)
There are plenty that would argue that even at this price, Duke Nukem Forever isn't worth a buy. Arguably one of the worst games to come out in the last decade, I'm inclined to agree with them save for the fact that Duke Nukem Forever represents the most perfectly obvious example of awful game design. If you have any interest in learning what not to do with an iconic video game franchise, you probably should study this one.