To activate and install Invisible, Inc. on Steam (if purchased from Humble Store)
- Visit http://store.steampowered.com/about/ and download the Steam client;
- Install Steam and create a Steam account;
- At the bottom left of the Steam client, choose "Add a game" > "activate a game on Steam" > enter your Invisible, Inc. Steam Early-Access key.
- Install and run Invisible, Inc.