Zombie
It’s not a secret that zombies are one of the most popular topics in the world of free games played online. They have been experiencing the boom of popularity since the 1990s, where films with them became the trend. And also, largely because of the super-mega-popular ‘The Walking Dead’ series occurred a decade ago (and its spinoff). Everybody likes to kill zombies because it is hard to feel pity or sympathy to some(thing)one that is already rotting, decaying, smells killing and tries to eat you. Or at least, to infect you. So shooting them is fun, from any point of view.