This is fairly simple. WASD or Arrow Keys to move. Kill the enemies and get the highest score possible! Post your highscore in the comments below! (Mine is 209). Pssssst. Hold down G to gain a higher score. Hehehehehehehe. Did you really think holding down G would be beneficial?
Credit to the FlyingDonut2099 for the healthbar. Credit to the Intellicow for some cool ideas.