Carl Sanford Joslyn Petersen is an American game developer. He is also responsible for writing Quake’s manual.
He is a well-known fan of H. P. Lovecraft, whose work he first encountered in a World War II Armed Services Edition of The Dunwich Horror and other Weird Tales found in his father's library. In 1974, Dungeons & Dragons brought his interest to role-playing games. He became a full-time staff member at Chaosium. His interest for role-playing games and H. P. Lovecraft were fused when he became principal author of Chaosium's game Call of Cthulhu, published 1981, and many scenarios and background pieces published thereafter. While working for Chaosium he co-authored the second edition of RuneQuest, for which he also co-wrote the critically acclaimed TrollPak and a number of other Gloranthan supplements. He authored several critically acclaimed RuneQuest supplements for Avalon Hill and Games Workshop. Petersen served as co-designer for West End Games' Ghostbusters role-playing game. He still plays and runs role-playing games, and is a frequent guest at conventions where he usually runs a freeform game of his own devising, and/or helps to run someone else's game.
He worked some time for MicroProse, where he is credited for work on Sid Meier's Pirates! and Sword of the Samurai. Between 1989 and 1992 he also worked on the video games Darklands, Hyperspeed, and Lightspeed. He also made some contributions to Civilization.
Petersen joined id Software in 1993 after being impressed by Wolfenstein 3D, and there worked on Doom, Doom II and Quake. His Lovecraftian influences also resulted in some changes to the monster designs for these games.
He left id Software for Ensemble Studios in June 1997. There, he has worked as a game designer on several of their Age of Empires titles, including Rise of Rome, Age of Kings, and The Conquerors. During this time, he was a frequent poster on the HeavenGames forums under the username ES_Sandyman. He ran an extremely popular series of threads, "Ask Sandyman", where forum members could ask him about anything they wanted.
Petersen was the Executive Producer for the movie The Whisperer in Darkness (2011) which was nominated for awards at the Chicago and Warsaw International Film Festivals. It was produced by H. P. Lovecraft Historical Society Motion Pictures in the style of a 1930's black and white horror movie.
He currently serves as the publisher of horror magazine Arcane: Penny Dreadfuls for the 21st Century.
In mid-2013, Petersen led a highly successful Kickstarter campaign by his company, Green Eye Games, to produce the Cthulhu Wars boardgame. Over US$1,400,000 was raised achieving over 3,500% of the initial target. This success allowed the creation of more figures, map expansions and additional scenario options. In most, if not all, previous Cthulhu games "you strive to avert the impending catastrophe. But in Cthulhu Wars you ARE the catastrophe! The Great Old Ones have returned to claim the ruins of Earth, and you are one of them!".  Green Eye Games also produced the unsuccessful Kickstarter project Cthulhu World Combat .
Petersen is a Mormon, but sees no conflict between his Christian faith and his design of games involving Satanic elements. While working on Doom, he said to John Romero: "I have no problems with the demons in the game. They're just cartoons. And, anyway, they're the bad guys.".
Sandy is married, has five children, and nine grandchildren.
- E4M2: The Tower of Despair
- E4M3: The Elder God Shrine
- E4M4: the Palace of Hate
- E4M5: Hell's Atrium
- E4M6: The Pain Maze
- E4M7: Azure Agony
- E4M8: the Nameless City
His favorite weapon in Quake was the Grenade Launcher; he also wore a white shirt and blue pants as his avatar.