Alien lifeforms aren't always just non-player characters, enemies or simple decorations. From time to time some games let us slip on creepy, gooey and downright ugly alien suits to play as cool aliens and extraterrestrial races.

The recent launch of Path Of Exile's open beta—a new hack & slash action RPG known especially for its enormous skill tree, as you can see in the pic above—inspired us to collect some of the best looking skill and research trees spanning a variety of genres. It's interesting to see how creatively devs can handle this…