Zero Gravity is an original arcade game written for Chromasette, a tape based magnazine from the early 1980's. Using keyboard controls to rotate the player's ship clockwise or counterclockwise in 45 degree increments and to thrust, the player controls their ship in a zero gravity enclose environment. The zero G environment means that the ship (once it's moving) will continue in that direction and speed without slowing down until counter thrusting is done by the player; however, the player will ricochet off the 4 walls surrounding the playfield. The purpose of the game is collect the space pods that will appear at random locations on the screen; a fast counting timer goes from 99 down to 0. If the player collects a pod before the timer runs out, they get points (the # left on the timer) and a new one is randomly place (and the player is left moving the exact same speed and angle as they were when they collected it). If the timer runs out, the player loses a ship (lost ships are shown in the upper left of the score area) until they have lost 5 total, upon which the game is over.
Many years later (I think the mid-1990's), Sheldon Hildebrand decided to see how easy it would be to take a small ML Coco 1/2 game and port it to the OS-9 Level 1 operating system. This is the game he chose, and it plays just like the original, with a key change (Sheldon used the ALT key for thrust instead of Q, so his port was done on the Coco 3... and can even run at double speed this way. This Coco 3 version is included in NitrOS9/EOU (Ease of Use) Edition), which you can download for free here.
Title: Zero Gravity
Author: Andrew Pakerski (original version), Sheldon Hildebrand (OS-9 version)
Publisher: Chromasette magnazine
Released: July 1983 (original), around 1995 (OS-9 Version)
Requires: Color Computer 1,2 or 3, 16K RAM