The object of the game is to rack-up points by jumping and running to catch money ($) while shooting everything that comes at you. There is no break in the action, you play until you lose all your hearts and die.
Use the mouse for aiming and the mouse button for shooting. Movement in this side-scroller is constantly advancing to the right, there is no turning back. However, the [A] and [D] keys can be used to slow down and speed up, respectively. Press the space bar, or [W] key, to jump. Press it again to double-jump.
In addition to money, you will find power-ups floating in the sky as you advance. All provide some protection from the never-ending waves of enemies that approach: items to increase your health, upgrade your gun, kill all enemies on-screen, and even grant temporary invincibility or rage.
As you advance across the randomly generated terrain, so does the bar at the bottom of the screen. When it fills completely, you advance to the next level. Although there is no break between levels, new and more difficult enemies will begin to appear as you progress.