The original "Space Patrol" game that went on to spawn various games: Heritage's "Star Trek: Adventure Gaming in the Final Frontier" (1978), Gamescience's "Star Patrol" (1981), and Terra Games' "Starfleet Voyages" (1982).
Although not officially licensed, "Space Patrol" made some tongue-in-cheek use of the terminology and setting of Star Trek, referencing Kirk, phasers, Klingons, landing parties and so on. At the same time, its ambitions went beyond Trek-with-serial-numbers-filed and also included references to Niven's Kzinti, Asimov's Foundation, Heinlein's Starship Troopers, Flash Gordon, Pournelle's Falkenberg's Legion and -- in a last minute addenda -- the new kid on the block, Star Wars.
The book is 38 pages, but only 14 pages of that are actual rules text, in three columns of 8pt type. The rest of the book is filled with illustrations and the 25+ tables required to generate characters and run the game. Sections include "Creating Characters", "Creature Creation", "Psionics", "Gravity", "Movement", "Equipment", "Learning", "Saving Rolls" and "Combat". There are no rules for starship-based combat.
Character creation was determined by rolling 3D6 to determine the basic attributes: Strength, Dexterity, Luck, Constitution, Charisma and Mentality. The values of these stats generally determine a value or modifier for task resolution. If the attribute is from 9 to 12, there is no modifier. For each point under 9, the player will subtract 1. For each point over 12, the player will add 1. Sometimes the result will require consulting a success probability table, requiring another role on percentile dice. Sometimes it will be compared to an opposed value, such as the defender in combat. Sometimes it will become a factor in further calculations, such as the use of the telekinesis psionic power. The "less than 9, more than 12" system is very consistent, but what happens next is not, depending on the specific task.
(description based on original material written by Robert Saint John for his Groknard Star Trek gaming blog)