Here is the updated game: cant figure out why the textures on the cargo crate wont show up, but ill figure that out later
https://drive.google.com/file/d/1iAoeH0OhdbGbSugR4euAhwwn1vizDwld/view?usp=sharing
Your game seems pretty nice ! 
Indeed I donât have mush time to have a look.
But quickly I would say :
- Maybe your issue on textures is due to relative paths⌠The error I get is about trying to open /home/enguerrand/Videos/Clips to Use/Animation/games/defend the factory/3g65cn8msbwg-Cargo-Crate/Texture/Cargo side redish.png where /home/enguerrand/ is my user path, and the rest is path to your texture⌠It means itâs a relative path. You might have moved your structure (moved the .blend or moved the folder which contains the .blend)
- By the way, try to avoid spaces in paths. Donât create files with spaces in file name, donât create folders with spaces in folder name. It will, sooner or later, create some problems, specially when you are sharing your stuff, considering that other people might use it on other OS, etcâŚ
- The meshes are quite weird, is it a scan ? Whatever, generally speaking, in Blender, the less objects, the better. For example you ground is made of a lot of objects, some of them even contain faces in walls and in the roof⌠Maybe you should merge all of it into one object.
- The gun shot sound is immedialty stopped as soon as mouse click is released. Itâs because the Play mode is set to Play Stop. Set it to Play End to fix that issue.
I guess there is a LOT to say again, but I have to go sorry.
Well done for what you have already achieved !
See you ++
Tricotou