A action game for the Sega Master System released in 1987.
You take the role of J.J., a member of the White Knights. Your mission is to invade the base of the Norsa Empire, gather their plans for destruction, free your captured comrades and demolish the facility.
Zillion was a side-to-side shooter game. You went for room to room, shooting Norsans, regaining life, and gathering powerups for your gun while searching for your captured friends and Norsan invasion plans. You usually had to solve some kind of puzzle to proceed to the next room or area. These puzzles involved negotiating laser barriers, moving walkways, land mines, and invisible infrared alarms to access inconveniently placed computers. Your Zillion gun (which inspired the shape of the SMS Light Phaser) could be powered up twice, increasing range and power each time. You acquired items by shooting cylinders to break them open. Grabbing the Opa-Opa increased your character's level. Eating bread gave you back health.
The game was well-designed with an appropriate increase in difficulty as you progressed in the game. The puzzles were interesting and tricky, but satisfying to solve. One drawback was that you had to start over from the beginning if you died to conserve your continues.
The most distinctive part of the game was the codes you had to remember (or write down) and enter in order to perform tasks such as opening doors, shutting off autoguns and laser barriers and using the teleporter. These codes were a permutation of four out of a set of ten weird symbols. I called these symbols by names describing their shape. ("M", heart, 8, "U", key, fountain, "Y", circles, squiggly, circle) It wasn't until I saw a Simpsons episode that I realized the symbols were the numbers 1 through 10 reflected horizontally over their leftmost point. I was only 9 years old when I played it, but I still think I should have noticed that playing that game for so long.
Zillion was an original title written by SEGA. It was followed by a sequel, Zillion II, The Tri Formation, a much lamer game with more action and less strategy.