I love this game!!1! I think it's a really creative idea. Some parts in the game actually got me scared, like when the Second Virus uses his shotgun after you beat the First Virus.
You should add these:
-More chat dialogue from the "Best Friend" like if you say you prefer Halo than Duty of Call then he would get into an argument ( you should rename Halo to something else lol )
-A little Dot ( small hitbox or something ) on the centre of your Antivirus, basically the target to where the Virus is aiming. Because it's really annoying when a bullet hits the edge of the Window of the Antivirus
-A Duty of Call icon should appear on your Desktop, like a Trophy for beating the first virus
-Customizable backgrounds! Use real photos from your PC to add it in the game!
I'm out of Ideas now