unzip it, and then you should see a _Data folder, and two files named .86, and .86_64
Type "chmod +x AShortHike.x86" in a terminal when you are inside the folder. Then type "./AShortHike.x86"
The first command makes this file executable, so you can run it. The second line executes it. I haven't really used chromeos so I don't know how their terminal stuff works, but this is how you would run it on linux.