Version 1.1.1, executable installer for first and second episodes.
Setup has its own instructions, so just run the ".exe", follow those, and you should be fine.
Once the game has been installed, run the executable in the game's main folder to run it.
The game uses mouse to navigate through the menus, and the keys used in-game can be reassigned in the options menu. The in-game default controls are:
WSAD/arrow keys to move
Q/E to switch and 1-4 to select weapon layout
Mouse aims and shoots
Change log v1.1.1: