Gabe Newell, the leading executive at developer Valve, revealed the theory of fun that the company used when creating the original Half-Life and explained why it worked very well for one game but failed to impress in Counter-Strike.The developer tells The Verge that, “we came up with this rule, which is the more ways in which the game responds to a player's state or player action is more fun. In Quake, you shot a wall and the wall basically ignored you. You saw a little puff, and then there’s no record of your actions.”
Valve decided to make sure that the wall would change and imbibed Half-Life with examples of this idea.
The same concept then failed to work in Valve’s Counter-Strike, where players actually seemed to like limited world reaction because the multiplayer concept forced them to focus on themselves.
Presumably, a similar theory of fun will be used for the much awaited Half-Life 3.