Thanks for the feedback! I'll see what I can do, but I can't promise I'll manage to implement everything as some things are more complicated than others. Changing speeds is easy, but top-down camera will require more work to look acceptable.
I actually tried making the bullet a child of the player, so it moves with the plane, but as it stays on the screen for much longer than in the original (and the viewing distance is much farther), it looks weird, wiggling from left to right. Maybe I'll make it an option.
As for the shader - I made a typo in the section I set the shader parameters in the actual game...
Right now I'll probably take a short break and try to finish and publish another project, which I had almost done but abandoned in favor of this one.