Game designers would do well to set up interesting situations where the player has the option of following the prescribed path or doing their own thing. Most games results, regardless of how you got there, are fairly finite. For instance, AI character X can live or die, character Y can live or die, and the armed guards may or may not be alerted. If AI character Z dies, the mission is a failure. So, given these finite outcomes (3 variables with 1 succeed/fail objective), you have a manageable number of outcomes. Even in a game like RDR where all the results are succeed/fail ultimately, it makes you feel like you have more control over how you're shaping the world, like how you let bad guy X go because he was really just duped by his brother, or prostitute Y felt the wrath of your shotgun because she was a conniving bitch, even if they didn't change the outcome of the game as a whole."
