Guide not written yet. We add one after we've played the game. For now, this is the developer's own description.
About Evil Invader
Evil Invader plunges you into a dystopian battlefield overrun by monstrous foes. Engage in heart-pounding, fast-paced shooting action as you fight relentless enemies with an arsenal of weapons. Strategize with power-ups, master enemy patterns, and level up to unlock devastating firepower in this intense survival challenge.
Description supplied by the developer via GamePix.