mortal kombat

I played MK9 with my friends and still I had much fun even thou I don’t like 2d fighting games. And I think about trying older titles of MK series. So my question is simple just like the title. Which games in the series are worth playing and which are not?

Mortal Kombat II Unlimited is a full scale hack of the Sega Genesis Mortal Kombat II game, Originally work on the hack ceased with version 07, but in 2011 version 1.0 was released which added many new graphical features. Added a combo system; Secret fighters now fully playable; Bosses now fully...

Has anyone seen it or at least known about it? Here at least it's quite unknown; apparently there were only 13 episodes and much less violence. I found the intro on YouTube. Nostalgic in a way.