Each game is of course different. Let's start from MK1.
MK1
Had seven fighters. One hidden fighter. And two bosses. The home platforms had blood, and non-blood versions. The SNES was all non bloody due to Nintendo's standards at that time. The game had one Fatality per fighter, and one pit.
MKII
This game had 12 fighters. Three Hidden Fighters, Two bosses. Three Pits. Two Fatalities per fighter, and some had more than two like Cage, Shang Tsung, and Sub-Zero. Everyone also had one Babality, and one Friendship. Two hidden codes in the game, plus, some speical moves can now be done in the air. All home versions were as close to the arcade as possible.
MK3
This game had everything MKII had, plus some new additions. The game had 14 selectable fighters, and one coded selectable fighter. Two bosses, and one hidden fighter. The new addition here is the Run button which allowed fighters to run up and do another new feature called an auto combo. Every fighter has his/her own set of combos. Every fighter had 2 Fatalities, and Kung Lao even had a third one, a Babality, a Friendship, and now two new finishers. Mercy, and Animality. There were three pits once again
UMK3
In UMK3 we had everything from MK3. The new addition here was the extra fighters added to the select screen. Making the total in the game to 19 selectable fighter, and three coded selectable fighters. Also UMK3 had two different versions, each version had a certain ammount of super hidden fighters. In UMK3 which was more widely distributed, there was only Human Smoke as a super secret playable fighter. In the Wavenet versions whcih was more popular, and found mostly in Chicago it had Human Smoke, and even Noob Saibot. Every fighter has 2 Fatalities, Babality, Friendship, Mercy, and Animality, with the exception of Ninja Sub-Zero, Ermac, Noob Saibot, and Ermac. They only have a small ammount of finishers. The Wavenet version is almost now extinct, with a few select machines still in arcades, or owned by people themselves. There are four pits in this version, and one hidden stage.
MKT
Trilogy was another upgrade to MK3, and UMK3. It added Baraka, Johnny Cage, Rain, and Noob Saibot. The Nintendo version was different from all other versions. It had fewer fighters. The Khameleon was a female ninja. The unmasked Sub-Zero was removed, and all of his moves were given to the Ninja Sub-Zero. All other platforms the Chameleon was a male ninja. Plus the original bosses were back in these versions along with MK1 Raiden, and MK1 Kano, MKII Kung Lao, and MKII Jax. The new finishing move here was Brutality were you would beat the opponent until they explode.
MK Mythologies
The first role playing adventure game where you play Sub-Zero, and go through various stages to help steal an amulet. All of these events are told through motion capture movies played by actors from previous MK games. Sub-Zero had countless moves, and two fatalities the Deep Freeze Shatter, and Chiropractor's Nightmare. The CD versions had a preview of the MK4 game. These events will lead up to what happens in MK4.
MK4
15 fighters here. Two Fatalities, and two pits. Every fighter has a special weapon they can use against their opponent. Wepons, and objects can be thrown at opponents too. The newest thing here are bonebreakers where you would crack, or bend the opponent's limg in an odd way to do damage to opponent. You could also step up, or step down in the 3D arena to dodge certain attacks. The endings in this game were more movie like. You could also choose from one of two outfits via a code. The home versions added Goro, and Noob Saibot as playable hidden fighters. Plus there were now four outfits to choose from, and a new level.
MK Gold
MK Gold had the same 15 fighters from MK4, and two hidden fighters from the home versions, but also had five returning fighters, and one returning hidden fighter. Bringing the total to 23 selectable fighters. Four new levels were added, one of the four was hidden through a VS Screen code only, or cheat menu. The endings were revamped to look more like a movie than before. The new fighters also got new weapons too. MK Gold is only available on the Dreamcast and is the closest to the Arcade in every way.
MK Special Forces
Another adventure game done by the voices of several of the MK actors from previous games. All motion activated. No live actors were used here. You play Jax, and are on a quest to locate Kano, and his gang and bring them to justice. This game was not as popular as the Sub-Zero version.
MKDA
MKDA changed the entire fighting system, and it also slowed the game down majorlly. A total of 21 selectable fighters. Half of them hidden in a Krypt which too was new. The Krypt you would earn cins through various modes of play, and buy the coffin to unlock them, or certain arenas, or MK things. There were also 2 super secret fighter. Every fighter had two fighting stances, and a weapon. There are only one Fatality per fighter, with the excetpion of the 2 super secret fighters. Plus, there is one non selectable sub-boss. Some fans like myself, do not like MKDA, or its predecessor.
MKD
Even though more fighters were added, bringing the total to 24, and two Fatalities per fighter, and numberous Pits, and a new suicide death move, the game play was still slow. No super secret fighters except on the Gamecube where Goro, and Shao Kahn were added. Much like MKDA, the gameplay was still choppy, and hard to control.
MK Shaolin Monks
Will be the next adventure game in the MK series. Not too much is known about this game except it revolves around Liu Kang, and Kung Lao's storyline. Unfortuneatly it does not look as promising as its predecessors.
But it did alot of stuff to the storyline.
