Plays inside your own copy of Portal 2, on your device, not in a browser tab. Opens github.com in a new tab.
How to play
Have your own copy of Portal 2 installed: the mashup plays inside it.
There is no release yet: get its code from its repository on GitHub and build it as its README says (it runs on Windows and Linux).
Install it as its page says. What it asks for is just below, in the list's words.
Start the game the way its page says: some mashups come with a launcher of their own.
What it asks for
Portal 2 with the example portal2_dlc3 folder and smolnes.nut copied into the game files; load map sp_a2_triple_laser via the console; the user supplies a ROM converted to a Squirrel array of hex bytes.