The Shrinkocalypse

Mark and Winter are both university students, and both have awakened a power since the night everything changed. Winter comes across as cold and is kinder than she looks. Mark's power is the Infinite Evolution System, which lets him grow stronger by absorbing biomass and by taking the abilities of whatever he kills. The two of them decide to stay together. The night in question is the one when every person on earth shrank to a few centimeters tall. Civilization stopped working, and the ordinary world turned into a jungle where nearly everything is big enough to kill them. Mark's system woke in him at a moment when he was about to die. They run into other awakened people who mean them harm, along with mutated animals, the infected, and a cult. What they learn along the way is that all of it traces back to crystals called Xeno-Cores, which are scattered across the world. Mark sets out to collect them.