Well, it already exists a excellent thread called MK Storyline analysis.
By seeing this, I decided to make an MK gameplay and kontent analysis thread.

I'll start with all the different gameplay the MK games offered us:

MORTAL KOMBAT1 :

This the beginning of the MK series. Though this game was 2D only, I found it great when it came out. There wasn't many choice in kombat as for the combos, they only existed as customized moves though they were very usefull in defeating an opponent. The endurances matches were very cool as this was a good addiction to the game and we had the motivation to face the hidden ninja, Reptile. The bosses were cool to fight: I didn't have the feeling the computers played as a bad loser. About the ending sequence:
Very simply done but very good too. The endings were good done and there was more fight to complete than the both playable and unplayable characters numbers.

MORTAL KOMBAT 2:

This game is MK1 with many improvements. More hidden characters to fight and the special moves are still usefull. For combos, we also had to find good chains. The endurances were missing: it's the only negative point about this game. The bosses were harder but still cool to fight. And we also had to fight all the characters before beating the game. About gameplay and finishers (I'll discuss this part later), this game kicked ass though it's not my favourite. I don't need to make any comment about the endings as it's done in the same way as MK1.


MORTAL KOMBAT 3:

ULTIMATE MORTAL KOMBAT 3:

MORTAL KOMBAT TRILOGY:
About endings: same as MK1 and 2. That's all. Though, the UMK3 endings show the character in versus pose with a text explaining his ending only.
This game had better graphics about backgrounds than the 2 former MK Games. And about combos: It's the best part of the game. There's still possible to make combos Ãa la MK1 and 2 but we could perform close hits + close hits and special moves. And each character had his combos series unlike MK4. Running was a great idea. The hidden characters chapter has been kinda given up. Smoke was only fightable thanks to a combot code in MK3, Noob Saibot only after defeating Shao Kahn in UMK3. But the endurances made a return but there were much harder. There were less characters to fight before beating the game: MK3 had 17 (playable and unplayable) characters and the max to fight was 12 , UMK3 had 25 characters and offered only 10 battles to complete. And MKT had 36 characters and only offered 10 battles.
The bosses were a difficult higher but not a pain in the butt. The idea of sending the opponent onto the upper floor was cool but not enough correclty done.

I'll discuss the next MK games later.