"Fatal Error - steam must be running to play this game"
As I am aware, many people out there buy a new game on steam, only to encounter an endless amount of problems before even diving in.
I am aware that one key problem people face is after installing a new game, when trying to play, the steam error appears "Fatal Error - steam must be running to play this game"
1) One of the easiest ways to sort this out is just run steam as administrator.
2) If you are a beta participator, simply opt out. This can often solve your problem. Go to settings -account - Steam participation
3) Verify integrity of the game. Go to library - select game - properties - local files - verify integrity.
4) Delete "ClientRegistry.blob" usually found - local disk (c:) - program files - steam etc..
5) Delete local content of the game. Go to library - select game - delete local content. Then re-install.
6) Delete and re-install steam.