Arcade: November 9th, 1997.
PC: July 31st, 1998.
PlayStation: 1998.
Nintendo 64: 1998.
Game Boy Color: February 28, 1999.

Playable Kombatants:
(Hidden Kombatants not included)

Arcade, PC, PlayStation, Nintendo 64: 15: First 3 rows of the select screen.
Game Boy Color: 8: Raiden, Quan Chi, Fujin, Liu Kang, Sub-Zero, Reiko, Tanya, Scorpion.

Hidden (Playable) Kombatants:

Arcade: Meat.
PlayStation, PC: 3: Meat, Noob Saibot, Goro.
Nintendo 64: Same as above plus Kitana. (Unlockable using a Gameshark code)
Game Boy Color: Reptile. (?)

Bosses:

Sub-Boss: Goro
(except Arcade and Game Boy Color)
Boss: Shinnok.

Finishers:

Each character can perform 2 Fatalities and 2 Stage Fatalities