In order to play the game locally you will need:
Download the latest version of ReCap from the Releases tab here in Github (Windows / Ubuntu).
After that, you will need to find the Darkspore.exe. Depending of your Darkspore version, its folder will be different:
Copy the recap_launcher.exe file from the ReCap release to the DarksporeBin folder. You will use it to launch Darkspore later on.
Run the recap_server.exe file from the ReCap release. While it is running, launch Darkspore with the copied launcher exe, and keep ReCap running while using it.
Press Singleplayer in the Darkspore launcher and wait for the login screen. Press the Register button in the Darkspore login screen, create a user account (it will only exist in your computer, and you won’t need internet to do that), and then login with your new user.