big or small. Then we'll get the theme of the characters, like ninja or robot. Then we'll design the costume, and while doing that we create the storyline and how s/he fits into the universe. Then we'll find an actor that kinda resembles our character." Tobias' writing and artistic input on the series ended around 2000 following the release of Mortal Kombat 4. In 2012, he said: "I knew exactly what I was going to do with a future story. A few years ago, I [wrote] a sort of sequel to the first MK film and an advancement to the game's mythological roots." The title Mortal Kombat was the idea of pinball designer Steve Ritchie, following difficulties trademarking the original title of Mortal Combat. Since then, the series often intentionally misspells various words with the letter "K" in place of "C" for the hard C sound. According to Boon, during the MK games' development they usually spell such words correctly, only making the substitution when one of the developers suggests it. Graphics The characters of the original Mortal Kombat and its initial sequels were created using digitized sprites mostly based on filmed actors, as opposed to hand-drawn graphics. Mortal Kombat games were known for their extensive use of palette swapping, which was used for the ninja characters. In fact, many of the most popular characters have originated as simple palette swaps. In the first game, the male ninja fighters were essentially the same character; only the colors of their attire, fighting stance, and special techniques mark a difference. Later games added further ninjas based on the same model, as well as several female ninja color swap characters initially also using just one base model. All of them gradually became very different characters in the following installments of the series. Eventually, Mortal Kombat 4 brought the series into 3D, replacing the digitized fighters of previous games with polygon models animated using motion capture technology. Hidden content Most Mortal Kombat games included secret characters, secret games, and other Easter eggs. The original Mortal Kombat was the first fighting game to introduce a secret fighter in Reptile, reached if the player fulfilled an obscure set of requirements. Future games would continue the trend of hidden characters. There is also a hidden game of Pong in Mortal Kombat II, and Mortal Kombat 3 includes a hidden game of Galaga. Many extras in the series