Once you purchase and install/download the Strategy Guide in the DLC list of Hardcore Cruising in your Steam Library, you can find the files for it in your Local Files. Right-click the name of the game (Hardcore Cruising) from the list of games in your library, click Properties, go to the Local Files tab, then click Browse Local Files. You'll find the Strategy Guide in this folder.

This Strategy Guide tells you what choices to make to get all the endings and achievements in the Hardcore Cruising game. It's a PDF file.