This game has debugging material.
Cowboy Kid manages to cram nearly every Western stereotype into a tidy four-megabit package.
Debug Menu Remnants
There might be code left, but it's unlikely...
A set of 8×8 metatiles and a palette is all that remains of a debug menu. Despite the lack of a corresponding screen layout, the menu's functionality can be inferred from the remaining text fragments: it would have allowed you to choose a starting stage, give yourself cash, customize your inventory, and choose how many hearts you start with. Note that the game's final boss, Scorpion Master, seems to be missing from the menu.
NOTE: A grid has been added to the metatiles below to help show the tile edges.