Troy is an Asteroids AutoLISP game driven by the grread function.
It can be run inside of an existing drawing. When it's finished, it purges all entities, styles and layers it created. You have three ships to use to shoot down as many Troys as possible. If a Troy runs into your ship, it blows up your ship and you loose 10 points. Each Troy you blow up, you gain its value in points. Use the mouse to keep the game moving. Pick the mouse to fire at Troys. Each fire cost you 1 point.
Press P to pause the game. Press Q to quit the game before it ends, in order to purge all entities, styles and layers it created. If you press the escape key to abort the game, simply rerun Troy again and select the Clear option. So do not press the escape key to abort the game.