This post contains some story-related spoilers, so beware.
The main game takes place on an island in a small archipelago, where you combat the Machines and survive as best you can. People have pointed out the fact that you can’t swim in this game, and I understand that this is how the game’s engine was designed just as it was with Call of the Wild.
For immersion reasons this can be explained quite easily; it’s late november in Sweden, waters are frigid and you’re carrying lots of equipment which slows you down. That’s all fine.
What gets me is that the game insists on a kind of urgency, you’re dropped into a familiar setting (especially if you’re Swedish) and you must do what you can to outlive the Machines and combat them while also searching for help, through the various missions you encounter. Ultimately you discover that the bridge to the mainland has been destroyed. So you’re stranded, right?
Not really. Because ingame, you encounter boats. Some docked, some stored away. From an in character perspective, there’s -nothing- stopping you from taking a boat to the mainland. During the game’s intro it hints that you’re attacked from the shore as you come back, but you do manage quite easily anyway. I realise this is a minor thing, but I thought that perhaps some kind of water hazard related to the Machines could prevent you from attempting leaving the island. A hint you recieve like… “There’s something in the water…”.
In Half-Life 2, they used Leeches to keep the player from swimming away from the shores. It’s simple, but it works. If the Machines were developed on an island, you’d think they had some kind of amphibious alternative. It would make for some amount of worldbuilding, even if it’s just a tiny mention in a diary somewhere, or perhaps gives you sightings of strange machines in the water if you spend much time by the shores.