When I was replaying ‘HL2’ around ten years ago, I ran around the whole map looking for where I can get outside of the plot course, especially in the slower parts of the levels. This culminated in me driving the hoverboat up a three-meter-high wooden platform, falling from that platform myself, and not being able to climb up again to get the boat. After which I had to run from the attack helicopter on foot, and swim by myself later on that level.

I use about the same approach in the original ‘Deus Ex’, which I've been replaying recently: investigating every nook and cranny, being 100% stealthy, trying to go where the game shouldn't allow me to be. I actually found an exit from a scripted part of a level where only one path is normally possible — though there was nothing to do outside of that part. The game also gives experience points for getting into some remote or secret places.

My opinion is the exact opposite. Narrative games, even action shooters, need to have high action and low action parts in balance. If high action segments are excessive, it can lead to combat fatigue. If low action parts are excessive, the player gets bored and the pacing dies.

Half-Life 2 E1, the "Low Lives" chapter, has probably the most stressful combat in the game because the player has to balance so many things. Shooting the zombies attacking Gordon versus helping Alyx fight. Helping Alyx versus keeping the flashlight charged. Firearms versus explosive props. All of that in oppressive darkness. Combat fatigue sets in. The short puzzle segments, even as simple as crawling through a vent to flip a switch, are opportunities to take a breath, absorb the environment, and prepare for the next segment -- especially at the end of that particular chapter, when the player escapes the zombies and has a chance to wind down.

At the same time, puzzles, by their slower nature, are excellent for delivering narrative and player training, and to let the player absorb the atmosphere. Alyx's first encounter with the stalkers in "Undue Alarm" wouldn't have had the same emotional impact if the player could just pop them in the head and move on.

In contrast, most of "Highway 17" is just a prolonged vehicle-based puzzle. By the time the player reaches the large railway bridge, they might be sick of driving. I know I was. It's a relief to finally engage in some platforming and long-range combat while traversing the bridge.

So what are the narrative values of my two examples? The cinderblock seesaw in "Route Kanal" is just player training. A show, don't tell method to let the player know that physics puzzles will be a factor. It's also a short break after the on-foot chase, before the encounter with the hunter chopper. In "Water Hazard", the contraptions serve a larger narrative purpose: they're the tools of the rebels' refugee evacuation effort. The player utilizes them like one of the refugees would have.