Hi Zakaria, thank you so so much for playing and actually trying to get a highscore! Had a lot of fun watching it. I see now that I have to explain the game better. The Special Timer and Kills count for every zombie you kill with gunshots. If you manage to get 6 Kills in 3 Seconds you will be rewarded with the special gun for some seconds (you had it at 9:31), which is the most important mechanic to get a very high score. I think I have to tweak the game somehow, because it makes a lot of fun when you just splatter dozens of zombies but most people don't get this far. So this was really helpful. Thank you a lot!
EDIT: There is actually a fullscreen option to toggle on or off on the title screen!