Gordon Freeman, the game’s protagonist (whom the player controls), is in trouble with Civil Protection, the law enforcement officers of the game’s totalitarian government, and has made the mistake of bringing a crowbar to a gunfight. To see the relevance of this model to Half-Life 2’s combat, one could look as early as one of the game’s first levels, Route Kanal.
The infographic below describes this tension structure by using Star Wars as an example (Portnow, 'Pacing'). More specifically, there is an initial rise in tension followed by a calmer period, followed by a rise, and the calm and tense periods alternate as tension mounts overall until the climax, after which tension falls to zero. In part, it states that a well-paced game is characterized by rises and falls in narrative tension. In order to approach this subject, it is useful to use the framework provided in Extra Credits’ episode on pacing. Half-Life 2’s varying combat difficulty plays a key role in shaping its narrative structure.