Note that some games on Steam are DRM free, you can download the game via Steam and then make a zip with the files for your own safekeeping. Sadly it isn't obv

Note that some games on Steam are DRM free, you can download the game via Steam and then make a zip with the files for your own safekeeping. Sadly it isn't obvious (nor mentioned anywhere, except some very incomplete lists in various wikis) which games are DRM free and which are not and the only way to figure out is to buy the game and try to run it outside of Steam (with Steam itself not running and its folder temporarily renamed to something else). In general if a game doesn't have steam_api.dll, it should be DRM-free but if it does then it is a crapshoot if the Steam integration is necessary or the game can function without it (e.g. Dementium II HD, a game i just tried yesterday, does have the DLL but it can work without it). Also some functionality that in theory could be available without Steam (such as multiplayer) will not work.