​I spent a while wondering how to fit the "running out of space" theme, then thought:

"I know what has lots of space: my hard drive. Let's fix that."

Hill Fill Phil is an endless runner in which Phil is trying to climb a hill, but you progress indirectly, raising the water level by filling your hard drive with files.

When you start the game (hit ENTER / SPACE), you'll be asked to choose a folder on your hard drive. Make sure this is empty initially!

Once the game starts, Phil will travel as far as they can until they stop at the edge of a chasm. To cross a chasm, you need to increase the size of your game folder, so it matches the target size.

The water level will rise, bringing the planks up to a level where you can cross the chasm and continue.

Warning: if you fill it too much, you will drown and the game will end!