since it's a new trend for the MK series, let's come up with subtitles for the older games if they were to be re-released with a makeover. And give a reason why...

Mortal Kombat - The Shaolin Tournament
It's the last true Shaolin Tournament before it gets hijacked and becomes a fighting tournament with out the sacred rules of MK.

Mortal Kombat II - The Emperor's Challenge
The beginning of Kahn's rule of the tournament, he challenges the survivors of the first to fight him.

Mortal Kombat III - The Grand Plan
The grand plan is where Kahn finds a way to takeover Earth with Earth's people to fight for their survival in another tournament.

Mortal Kombat IV - The Fallen
The fallen is the fallen elder Shinnok and the state of MK which has become corrupted, Shinnok takes hold of the tournament with Quan Chi.