Here I will basically describe how easy and fast it is to beat the game in about 1h and 30 min.

Controls:

-you're on the better side if you play with a controller
-you should really look up the controlls first cause actions are on very strange unusual buttons
-give yourself some time to get used to these controlls (after like the 3. level you will play like a pro ;D )

Gameplay:

so your job is to just shoot these strangers that got guns and are attacking you, until you reached a certain amount of kills ( shown on the top of your monitor ). After you've done that you can press a button ( F1 on the keyboard ) to end the level.


Guns:

for my playthrough I only used the standard machine gun ( with endless ammunition ), the auto shotgun ( you get that a bit later in the game ), the rocket launcher ( very effective against strong enemies or a group of them ) and grenades ( a bit difficult to throw but you get used to if after short time )

Just some words for the end:

Thanks for reading this far, I hope my guide helped you a bit by beating the game.