Alien Nine is certainly worth a watch if only because it is very short and very strange, in an intriguing way. I don't necessarily think it's the best storytelling or writing ever but the mechanics and creatures of this world are so interesting that it elevates the rest. The designs are fascinating and distinct, the weird alien helmets and their long combat drill-tentacles alone are so unique and cool without even considering the larger aliens they fight. The weakest point is that it ends very abruptly and the characters have little to no development. There's a manga but it's not terribly good and this short series almostfeels better if only because it contains all the good without dragging it out.