Could be the basis of something sweet. Extra point from me as a fellow assembly programmer / masochist. Something rather charming about the sprites. 

Having played through this in single player, I can say that there's a basis for a game here for sure. It reminded me of a very basic version of a side-scrolling run and gun such as Robocop. I feel that this can be expanded upon, add in some more enemy types, perhaps some environmental obstacles for the player to traverse? There is definitely a core game loop here, and it certainly works.

The adf should have been bootable but I can forgive you for that. I really liked the player sprite, it had a lot of charm and reminded me of Basil Brush. (If you don't know look him up.) Games don't need to have amazing pixel art and I dig your graphics. However the gameplay is pretty basic to say the least. Curiously every time the game played a sound sample my floppy drive would spin up which was kinda weird. The game is written in ASM though, which is more than I can do, and you have the source on github so I have to give you some extra points for that.

Thanks for the effort, however the game lacks in every possible departament. It can be completed in five minutes and basically does not leave you with anything that makes you want to try again. Maybe it works as some kind of proof of concept or a protype of the game  engine but I can hardly name it a game. Sorry for the harsh words but I try to be objective.

i liked the sfx. for a run n gun needs more bullet hell speed. 

Nice concept of 2 player co-op  run-and-gun  game!

FYI: The fire button doesn't work on an A4000 configuration for either player, but they work fine on an A500 configuration. The ADF was not bootable and it also did not include a startup-sequence file.
(Used WHDload GenericKick13.slave to run on A4000)