Text-based games trace as far back as teleprinters in the 1960s, when they were installed on early mainframe computers as an input-and-output form. At that time, video terminals were expensive and being experimented as "
glass teletypes", and the user would submit commands via the teleprinter interfaced with the mainframe, the output being printed on paper. Notable
early mainframe games include
The Sumerian Game,
Lunar Lander,
The Oregon Trail, and
Star Trek. In the mid-1970s, when video terminals became the cheapest means for multiple users to interact with mainframes, As with other games, they often lacked functionalities such as
saving. Proposed reasons for the absence of the ability to save included the fact that early computer games were often simple and gaming sessions were brief, as well as hardware limitations and costs. This may partly explain why earlier computer games were developed instead under the episodic structure, but such computer games whose
source code could be accessed by anyone could be
modified, and as designers wrote larger game worlds, gaming sessions lengthened, and the need to resume where left off became inevitable. This started in 1977 with
Don Woods' revision of the 1976 text-based
adventure game Colossal Cave Adventure (later renamed to
Adventure), which saw expanded gameplay and story and, notably, the ability to save. Text-based games were also early forerunners to online gaming. From the late-1970s Without a graphical program for clients, most online computer games could only run using textual graphics, However, terminal emulators are still in use today, and people continue playing
MUDs (multi-user dungeon) and exploring
interactive fiction. The
Interactive Fiction Competition was established in 1995 to encourage development of and explore independent interactive fiction titles, and has since held annual competitions for who can develop the best such game. == Genres ==