Half Life 2: Prison Break

Requires Half Life 2 in order to run,  unzip the folder, copy it to this folder C:\Program Files\Steam\Steamapps\common\half-life2\hl2\maps. Then, start the game and press the tilde key (~) to open up the developer console. If the console does not come up, go to your options and go to the keybindings tab, and press the "Advanced" button. A small window opens up and check the box that says "Enable Developer console". Now you will be able to open the console.

Once you open the console, type in "map" and then put in the file name of the map after that (excluding the .bsp extension)