Damorange-Man is a maze chase video game. The player controls the eponymous character through an enclosed maze; the objective of the game is to eat all of the dots placed in the maze while avoiding four colored viruses — H1N1 (Henry), Marburg (Mike), Rubella (Ruby), and Pneumonia (Phil) — that pursue him. When all of the dots are eaten, the player advances to the next level. If Damorange-Man makes contact with a virus, he will lose a life; the game ends when all lives are lost. Each of the four viruses have their own unique, distinct artificial intelligence (A.I.), or "personalities"; Ruby gives direct chase to Damorange-Man, Mike and Phil try to position themselves in front of Damorange-Man, usually by cornering him, and Henry will switch between chasing Damorange-Man and fleeing from him.
Placed at the four corners of the maze are large flashing "syringes", or "vaccines". Eating these will cause the viruses to turn blue with a dizzied expression and reverse direction. Damorange-Man can eat blue viruses for bonus points; when eaten, their eyes make their way back to the center box in the maze. Eating multiple blue viruses in succession increases their point value. Blue-colored viruses will flash white when they are about to turn back into their normal, lethal form. Eating a certain number of dots in a level will cause a bonus item, usually in the form of a fruit, to appear underneath the regeneration box, which can be eaten for bonus points.
The game increases in difficulty as the player progresses; the viruses become faster and the energizers' effect decreases in duration, to the point where the viruses will no longer turn blue and edible. To the sides of the maze are two large "warp tunnels", which allow Damorange-Man and the viruses to travel to the opposite side of the screen. viruses become slower when entering and exiting these tunnels. Levels are indicated by the food icon at the bottom of the screen.