Between all the running and riding in little boats and more running you end up covering quite a lot of ground in Half-Life 2! What makes this somewhat unique, though, is that you do it all in immediate succession.
There's no cutscenes where you jump in a helicopter and reappear 1,000 miles away, or hitch a ride on a tank for a few days. Every area you enter leads on from the one you just left, meaning it's possible to draw up a map of the entire game.
Like this one! You lose most (well, all) of Half-Life 2's beauty, but that's more than made up for by the sheer scale of the thing.
That, and the dawning realisation that you end up spending the majority of the game going the wrong way.
You can expand the map into a readable size by clicking on it, but to get the full thing you can hit the link below.