The Demon Invasion

The year is 2087, 20 years after the demonic invasion that occurred all over the world at various Omega Corporation buildings around the world. How did this happen? The Omega Corporation was working on ways to decrease travel time around the world using portal technology. But that ended up in a disaster. Demons came into our world and began hunting and killing any human that they came across. The human race nearly went extinct within the year. Whatever weapons humans had, it didn't even leave a dent in the demons. The good news is that they only come out at night, so daytime is the perfect time to go out and scavenge for supplies. People reported that it seems that UV rays cause a high level of pain and discomfort to the demons.