Xtrek

Xtrek is a text adventure that originated from Star Trek-based erotic fan fiction, leading to the emergence of a genre sometimes referred to as "adult interactive fiction" (AIF). The player controls a male Ensign named Marty Stu, a fresh Star Fleet Academy graduate, assigned to temporary duty on board the Enterprise. Under supervision by Counselor Deanna Troi, he will be evaluated in his ability to fulfill tasks assigned to him by superior officers to their satisfaction. If successful, he will receive a permanent posting to this position, achieving what can be called "satisfaction" as well...

The text parser is rather limited, and there aren't a great many options available to the player; in addition to the standard navigational directions, they will be expected to take objects, give objects (including, ahem, "head"), and there is also a special verb employed in this game beginning with the letter f.

At no point in the game does it become necessary to reverse the polarity through the main deflector array; these are not the kinds of problems the player is posed with; rather, they tend to deal with issues such as who to use a given object on or (ahem) in. Missing the point of intercourse, the sex scenes are non-interactive; the game's puzzles are just the removal of obstacles allowing the scenes to be triggered through use of the magic f-word.