I'm a Doom WAD freak so this was right up my alley. The vehicular gameplay takes some getting used to so but I like it. The only thing I'm a little disappointed by is that the water itself doesn't bob up and down, and I'm not sure if GZDoom has a simple way of letting you do that without extending the engine.
I'm looking forward to seeing where it goes, this looks like it would benefit a lot from a simple story to string a bunch of the levels together. The artstyle is also solid, I don't have any complaints about that it already looks great. Thanks for uploading the IWAD as well, works great on Manjaro.