The main interface class is named SteamNetworkingSockets, and many files have "steam" in their name. But Steam is not needed. If you don't make games or aren't on Steam, feel free to use this code for whatever purpose you want. The reason for "Steam" in the names is that this provides a subset of the functionality of the API with the same name in the Steamworks SDK. Our main reason for releasing this code is so that developers won't have any hesitation coding to the API in the Steamworks SDK. On Steam, you will link against the Steamworks version, and you can get the additional features there (access to the relay network). And on other platforms, you can use this version, which has the same names for everything, the same semantics, the same behavioural quirks. We want you to take maximum advantage of the features in the Steamworks version, and that won't happen if the Steam code is a weird "wart" that's hidden behind #ifdef STEAM.