Thanks for playing and for all the feedback, very much appreciated!
The current work-in-progress (v0.4) is going to overhaul the shaders and particles, so hopefully the effect of the upgrades will feel more impactful after that. That should also fix some of the weird textures, especially after reload. I don't have an ETA for v0.4 but it will come :)
Regarding the lack of mud on the windows and glass, there is some lore to that, and will be explained in more story in future levels. I plan to have about 5 levels / maps in total by the end, with lots more secrets, easter eggs and more. This is just a demo to hint at the systems to expect in the full game.
I'll add the rest of your feedback and suggestions to the todo list and investigate as I progress.
Thanks again for playing and well done one 100%!
p.s. thanks for pointing out the game version typo. It is 0.3 you were playing, I just must have forgotten to update the text there.