This project contains three scripts to help working with the steam-runtime, especially outside of Steam.
See these blog posts for more details:
A script to download the runtime, but only if it has been updated since last time.
A script to extract the important bits of the runtime, skipping the huge amount of documentation present (and optionally, the binaries for irrelevant architectures.)
A simple launcher script for your game to ensure your game executes inside the steam-runtime, and to aid in running it under gdb.