Secret World is a dying mmo with a cool (albeit unfinished) story and cooler puzzles. It is set in an urban fantasy world where magic is real and most every conspiracy theory is true in some fashion. Working for one of the big three - the Templars, the Illuminati, and the Dragon - the player character is tasked with investigating and containing occult disasters across the world. Wish it wasn't dying but good thing is you don't need to play it as an mmo to experience the story content. Hope you know morse code.
Yeah it was a lot of fun but impossible to play single player and I could never find any people to create a squad with :(
Then I have good news for you, the new Secret World is way easier (enemy HPs isn't balanced for parties anymore). So you can definitely SP it.