I used a polygon collider. There is a function in unity called CreateMesh() that lets you generate a mesh from its vertices. Then I just move the vertices everytime a bullet hits it and regenerate the mesh. It is a really basic solution though for breakable walls, because sometimes it is pretty glichty.

Thanks for the good feed-back! With the controls you mean that you have to hold right mouse to shoot? And yeah the different audio pieces all have a diffrent volume, already noticed that when testing shooting around, but did not have the time to change that in the end.

Hey thank you, a tutorial is provided on the itch.io website. I'll look into your game!