Build and Buy modes follow a square-tile system in which items must be placed on a tile. Walls and fences extend along the edge of a tile and can follow the edge of the tile or cross it diagonally, but furniture items cannot be placed on either side of a crossed tile. The base game contains over 150 items, including furniture and architectural elements. In addition, the game includes an architecture system. The game was originally designed solely as an architecture simulator, with the Sims there only to evaluate the houses, but during development, it was decided that the Sims were more interesting than originally anticipated, and their once-limited role in the game was developed further. Players have a broad choice of objects that their respective Sims may purchase. Objects fall into one of eight broad categories: seating, surfaces, decorations, electronics, appliances, plumbing, lighting, and miscellaneous. Development The original inspiration for The Sims was Christopher Alexander's 1977 book on architecture and urban design, A Pattern Language. Game designer Will Wright was inspired by the book's focus on functionality in architecture, as Alexander based his design principles on structural usability rather than aesthetic values. Wright wanted to create a simulation game about enabling human behavior and interaction through design. Scott McCloud's 1993 book Understanding Comics became a big influence on the design of The Sims later on, as it advocates a certain type of "collaboration" between designer and consumer and outlines the value of abstraction for getting readers or players involved with a story. Will Wright started working on The Sims after releasing SimAnt in 1991. It was during that same year that he lost his home during the Oakland firestorm of 1991, and he incorporated his experience of rebuilding his life into the game. However, the game's concept was very poorly received by a focus group, so Wright had difficulty getting the project off the ground. He managed to convince his company to let him work on the project (codenamed "Project X" at the time) in the background while developing SimCity 2000 and SimCopter. He was lent one programmer for the project, Jamie Doornbos, who went on to become the lead programmer for The Sims. During the first few years of the project, Wright and Doornbos were primarily developing an open-ended system of character behavior. As the project continued, Wright found that the social aspect of the game turned out