Thanks for the feedback - you're absolutely right about the fire rate, I should've made them fire slower to allow the player to counter/beat them in a far easier way than having to struggle with positioning first. I definitely could've improved the game by adding a 'information' screen before actually playing the game to explain the situation better! So, the scientists are the only 'good guys' other than the player and you don't want to shoot them but the green mutants you mention are aliens that are immune to damage and instead use the energy of your attack/projectile and send it back at you with great damage. Now that you mention getting close, I really should've gave some enemies melee attacks if you get too close!