Thanks for fixing the build! I ended up ravaging all of the underairport on hard difficulty. Got all 8 upgrades in one run and just smashed through everything. Auto reloading actually exists and helped quite a lot :D
There is a marker on the map, yeah I could see it, but it's super small, like 1 pixel or something, too little. I guess after I defeated the Blucifer, I took his place and now terrorize the airport myself. Good game.