Steam is running a winter sale and I got these two gems.
Street Fighter V = https://store.steampowered.com/app/310950/Street_Fighter_V/
Contra Anniversary Collection (thanks to dano) = https://store.steampowered.com/app/1018020/Contra_Anniversar…
Contra (Arcade)
Super Contra
Contra (NA)
Contra (JP)
Super C
Contra III: The Alien Wars
Operation C
Contra Hard Corps
Super Probotector Alien Rebels
Probotector
Castlevania Anniversary Collection (thanks to dano) = https://store.steampowered.com/app/1018010/Castlevania_Anniv…
Castlevania
Castlevania II Simon's Quest
Castlevania III Dracula's Curse
Super Castlevania IV
Castlevania The Adventure
Castlevania II Belmont's Revenge
Castlevania Bloodlines
Kid Dracula (never released in English before)
History of Castlevania - Book of the Crescent Moon
Sounds like there is a hidden cost with Street Fighter V because you will need to buy the Upgrade Kit and\or Character Pass so it is up to date with what everyone else is playing with. Though even that seems a little obfuscated and it's not really clear which kit or passes you really need.