In honor of Earth Day 2012, Dark Horse Comics is offering a FREE digital copy of Brian Wood and Kristian Donaldson‘s The Massive one-shot.

Collecting parts 1-3 from Dark Horse Presents, The Massive tells a story of three people whose lives were changed as a result of the environment. These three made it their goal to each become environmentalists on a mission to save the planet after the world has already ended. And Dark Horse is giving you the opportunity to read the comic that acts as a prelude to the upcoming series in a paperless, eco-friendly way for absolutely no cost.

Swamp Thing is a character who blurs the lines of regular man who looks like a monster, a straight up piece of vegetation that looks sort of like a man, and both of things but also an eco-terrorist of sorts, but no matter how you view the character, it’s impossible to deny the fact that some of the greatest writers in comics have either written him or his ancillary characters. Also, when he’s not questioning his identity, he’s a pretty eco-friendly dude. So, it’s with this fact that Comixology is offering a 99 cent three-day sale on Swamp Thing for this weekend’s Earth Day.

Comixology has recently made these sales more manageable if you don’t exactly know what you’re looking for and have places different comics into sections that categorize them more efficiently than just, “Here’s a bunch of comics that are on sale.” These different sections for Swamp Thing are: