It works, too. You’ll find yourself considering the decisions you have to make more fully. Beyond the act itself (should Sam Fisher kill an innocent?), questions of trust (how will this affect my standing with the NSA?) and consequence (how much harder will this make my next mission?) become real factors that create real tension and relief – especially when people close to Sam hang in the balance.

That said, your decisions have a limited effect on the story itself. The between-chapter videos and expository montages that drive the story do change to reflect your actions in previous missions, but they’ll always set up the next mission the same way. There are also a couple of big “to kill or not to kill” moments that will affect which of the three endings you see, but that’s about it by way of plot influence.