The Windows build is 19MB, the MacOS build is 22MB.

The Linux zip file is 252 bytes only. Spot the error.

(Downloaded the zip). That note file in the zip archive is just an insult. With Unity the effort to do a Linux build for real is just the same as for MacOS, install the module for the Unity editor, then switch the target platform in the build settings, and click on build.

Really fun game, I love the recoil mechanic and the music was nice, I like it, good job! 

fun game

i feel like you could have maybe tweaked the physics a bit though

maybe make it so that your direction is influenced a bit by what direction you're facing like in Team fortress 2 which seems like an inspiration for this game already