Isn't this an admission that MK can't work as a movie? Like sure, MK can work as a movie, if you drop the plot and setting and just take the characters and have them do something completely unrelated to the tournament.
Or, you simply tweak it a little. Introduce Shao Kahn like he's Darkseid.
Picture this: the guy is sending in a practically demonic army through portals, so conventional and even guerrilla warfare simply doesn't work because the guy can literally send what amounts to a platoon of assassins literally anywhere on the planet without any forewarning.
For all intents and purposes, this is a war Earth cannot win and practically already lost. Our enemy is literally based in another dimension, so we cannot go on the offensive unless we figure out how to do that ourselves. This also precludes us gathering reliable intel even on the scope of the enemy's forces, but the simple fact that they employ portals so liberally means that they must be presumed to have a massive technological advantage. That portal 'tech' also means that an effective defense is practically impossible. It all but negates the range advantage of missiles, guns, artillery, etc, eliminates their need for a vulnerable supply line, and makes their troop movements completely unpredictable. They could literally just pop into a barracks and slaughter our troops in their sleep. Never mind the seemingly magical capacities of some of their more prominent war assets. So basically we've got Half-Life's Seven Hour war going on; capitulation is the only obvious option for a chance of survival.
Cue now Shao Kahn calling in to gloat and solidify his victory. By his reckoning, Earth's performance was
remarkably humiliating, it's like the world didn't even know how to fight. So in order to completely crush the planet's spirit he's trying a gambit to show its people how absolutely outclassed they are. So he - in his infinite magnanimity - is pulling back his forces and is opting to let the two worlds show their strength with their choice of champions in a tournament with the prize being glory and the planet itself. He expects to be entertained, and will be very disappointed if Earth holds its best in reserve...(at which point he calls out Johnny Cage specifically, having intercepted some video of his films and mistook the actor for a real fighter...whoops).
Et voila. Outworld sends in champions because Shao Kahn is trying to break Earth's will to fight (with a method partially based on him simply operating off a different military paradigm and consequentially not understanding that Earth wasn't holding back but was just outclassed), Earth sends champions from the military (Jax, Sonja Blade, probably Kano in Suicide Squad style parole), Johnny Cage has to attend due to a misunderstanding and not wanting to provoke Kahn, and a few volunteers like Liu Kang because it's the goddamn apocalypse and there will be at least a few good fighters who won't take that lying down.
The idea naturally needs polishing, but the basic framework is certainly workable. You aren't going to win any awards with it, but you can at least get a fun B-movie out of it and avoid the Razzies.
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Tangent: Raiden does not (explicitly) appear for the Doylist reason that the lore starts getting too dense for one movie and the Watsonian reason (addressed if he appears in a later film) that the Celestial Bureaucracy (yes, I'm using Chinese mythology for this, because this explanation amuses me) is being...well, the DMV. By which I mean they're not present in the movie because the gods are bickering about whether or not the rules allow them to intervene, and the pro-interventionist gods have to get a motion passed and the necessary forms signed in triplicate before they can so much as send down a proper avatar (though Raiden
might be exploiting a legal loophole and giving promising champions a bit of a nudge under the radar).