You're a cowboy on the run from hostile creatures called Slymoids. As they approach from the horizon, they'll be joined by ones that are flying towards you from above. When airborne, these flying Slymoids will move back and forth across the screen as they make their way down to the bottom. You can take them out while they're in mid-air or on the ground.
The game is set in a sprawling environment where you'll navigate through different areas - coastline, city streets, and underground caverns. The gameplay moves as you do, with each area scrolling by. Be aware that there are moving obstacles like falling stalactites in the cavern section. Manage your time wisely to avoid getting overwhelmed by enemies coming from all sides.