Fuelled by endless science-fiction content across formats, from feature films to novels, aliens have been a huge part of popular culture even if their existence is debated through eccentric conspiracy theories. Our fascination with extra-terrestrial objects and aliens isn’t limited to fiction as Unidentified Flying Object (UFO) sightings have been reported across the globe.

Among the most popular is the Roswell UFO incident that took place in 1947. Every year, spirited enthusiasts celebrate World UFO Day on July 2 to coincide with the highly speculative event. While the unexplained aerial phenomenon remains unproven, interest around the crash hasn’t died down, with hundreds of theories floating around. It comes as no surprise that every year we are treated to many alien-themed movies, TV shows, books, and video games. On World UFO Day, we have rounded up some of the best alien invasion games for you to check out.