Really cool concept that works well! I did notice some bugs (the worst one I found was that tanks would stop at the invisible barrier to try to shoot my farthest turret, but no bullets would pass through so they'd just be shooting at each other until I sold the turret), but nothing too game breaking. I also liked the pixel art! I think the UI could have benefited from also being pixel art to make the game more cohesive, but it still looks good as is. Solid work!