The 30th Anniversary collection compiles 12 games as they appeared in the arcades, including the original Street Fighter, the many iterations of Street Fighter II, the three different Street Fighter Alpha games, and Street Fighter III and its two immediate sequels. Some may argue that this actually is four games and its upgrades, but some of the character movesets and attacks vary significantly between the different chapters (for example, Dhalsim didn’t originally have his teleportation ability).
Source: N4G PC Street Fighter 30th Anniversary Collection review – ChristCenteredGamer