bundled game with the system. While the Colecovision only had 17% of the hardware market in 1982 compared to the Atari VCS' share of 58%, it outsold Atari's newer console, the Atari 5200. A few games from this period have been considered milestones in the history of video games, and some of the earliest in popular genres. Robinett's Adventure was inspired from the text adventure Colossal Cave Adventure, and is considered the first graphic adventure game and the first action-adventure game, and first console fantasy game. Activision's Pitfall!, beside being one of the more successful third-party games, also established the foundation of side-scrolling platform games. Utopia for the Intellivision is the first city-building game and considered one of the first real-time strategy games. Early hobbyist computer games The fruit of retail development in early video games appeared mainly in video arcades and home consoles, but at the same time, there was a growing market in home computers. Such home computers were initially a hobbyist activity, with minicomputers such as the Altair 8800 and the IMSAI 8080 released in the early 1970s. Groups like the Homebrew Computer Club in Menlo Park, California envisioned how to create new hardware and software from these minicomputer systems that could eventually reach the home market. Affordable home computers began appearing in the late 1970s with the arrival of the "1977 Trinity": the Commodore PET, the Apple II, and the TRS-80. Most shipped with a variety of pre-made games as well as the BASIC programming language, allowing their owners to program simple games. Hobbyist groups for the new computers soon formed and PC game software followed. Soon many of these games—at first clones of mainframe classics such as Star Trek, and then later ports or clones of popular arcade games such as Space Invaders, Frogger, Pac-Man (see Pac-Man clones) and Donkey Kong—were being distributed through a variety of channels, such as printing the game's source code in books (such as David Ahl's BASIC Computer Games), magazines (Electronic Games and Creative Computing), and newsletters, which allowed users to type in the code for themselves. While hobbyist programming in the United States was seen as a pastime while more players flocked to video game consoles, such "bedroom coders" in the United Kingdom and other parts of Europe looked for ways to profit from their work. Programmers distributed their works through the physical mailing and selling of floppy disks,