Ping a friend and play multiplayer using Steam's built in Remote Play feature! This cool feature allows you to play Extrorb's awesome local multiplayer mode with any of your Steam friends, even if they don't also own the game.
Setup
Once you have it running, the remote friend should have their controller set to Controller 2 and then set your controller to Controller 1. Whomever is Player 1 can choose to still use the keyboard, but Player 2 will always need to be set to Controller 2.
Connection/Lag
This whole setup really depends on your internet connection and the Steam software to run correctly. Try to select a lower stream quality option if you experience lag on the remote computer.