FaceBall 2000, a 3D first person shooter, made its debut as a Nintendo Game Boy title back in 1991. It did have an earlier incarnation for the Atari ST computer called "Midi-Maze." It's an abstract game of polygonal emoticons known as "smiloids" navigating mazes and shooting balls at each other, uttering "Have a Nice Day" when they score a hit. With a link cable, 4 Game Boys, and 4 copies of the game, up to 4 players may play simultaneously. A 2 player version appeared on SuperNintendo in 1992 with enhanced graphics, sound, and gameplay which exploited the 16 bit capabilities of that system. More obsure versions were later released in Japan; the Sega Game Gear edition which was a colorised hack of the earlier Game Boy edition and the PC Engine version, simply known as "Faceball" was a demo which featured more childlike depictions of the smiloids and "Battle" or "Race" style arena matches. This title is no longer available in stores but ROMs for all of the above versions have appeared on the internet. A brand new version known as "Faceball 3000" has also appeared on Shockwave.com. Blue Planet Software, formerly known as Bullet-Proof Software, developed this game.

From my review on i-mockery.com

It's hard to believe... and rather amusing... but there was a first-person shooter released for gameboy even before Wolfenstein 3D came out. Naturally it hasn't withstood the test of time very well- with its dazzling 8 fps animation, choice of one weapon to choose from, and lack of a strafe button, gameplay is reminiscent of dueling with heavily-loaded shopping carts armed with nerf guns, underwater. Except that your bullets don't fly straight up. All the same, I bought it as soon as it came out, and loved it. I would have given my left kidney for a friend geeky enough to own it as well, so I could kick his ass in Arena mode.
C'est la vie.