Shareware Games: For a brief period the shareware model defined how most games were sold on the PC, particularly those from smaller developers unable to land a contract with the big publishing houses of the time. Any game sold through shareware distribution is acceptable. Bonus points for playing the actual shareware version!
Famicom Exclusives: The wild popularity of the Famicom in Japan means there are a lot of strange and wonderful gems to be dug up and enjoyed by western gamers. Or maybe you want to play some of the console's more bizarre and and obscure shovelware? I won't judge. This category is for games that just didn't make the leap to the NES for whatever reason.
"Inferior" Ports: When it comes to porting games to various systems there tends to always be a port that is considered the best of the bunch, especially when games are ported to platforms that are woefully underpowered and require some creative design solutions to pull off. Give some lesser-versions of games a shot and see if there are any redeeming features.
Fangames and Romhacks: The worst thing about our favorite games is that they eventually end and we have to wait for developers to give us more. Or do we? Sometimes fans take it upon themselves to continue the legacy of a series, or just want to express their love by putting forth their own work.