I would just like to clarify that steam does not have to be online to play the games you have, it is the game companies that make their games drm and those are the ones you have to play online valve has or steam you call it has an offline mode to,so games you bought that are not drm you can play offline.
The details are on the store page to let you know if you need internet or not.If it says steam play then you can still play games offline just have to have steam running.I have over 800-900 games on steam.I have lots of drm and non drm and lots with there own launchers.easy make desktop shortcut run it from there if you don't want to have steam on,Just read before you buy games it will let you know if you need internet or not.
Steam is not drm some games are that gaming companies put on steam.
Hope that helps thanks.
P.S They also have lots of free2play games now.