From the manual of the game:
The object of the game is to keep your man, TRON, alive and scoring points. Keep him moving from side-to-side and floor-to-floor. Send him up the elevators. Jump him down a floor. Or slide him down the center INPUT/ OUTPUT beam. Wave after wave of Master Control Program attackers must be avoided - deadly Recognizers and Grid Bugs, even cannon-firing tanks. At the start, TRON has 4 lives, 1 on the screen, 3 in reserve.
You'll play one man at a time. Alone, your man TRON must avoid attackers on a grid with four floors. Keep him moving, keep him healthy - riding up the elevators, jumping down floors. Have TRON hitch a ride on a Solar Sailer! Points are scored my maneuvering TRON into position to intercept flying "bits" floating by overhead. Top floor points count extra. Stay alert! There's no place to hide.