With Serious Sam 4 you once again get to play as Sam "Serious" Stone as a member of the Earth Defense Force in their fight against Mental. This being is so powerful that it has enslaved several civilizations and uses them to wage war on others it seeks to dominate. Humanity and Earth is the latest focus of his interest, but thanks to the efforts of the EDF, his conquest is not going as smoothly as he likely would prefer. Partly this is because of the bravery and ability of soldiers like Sam and his team, but also because of a concerted effort to collect known historical artifacts that are now believed to be alien in origin and sources of great power. The entire goal of the game is to acquire such an artifact and then defeat the leaders of Mental's armies on Earth, but you can expect some hiccups on the way.