A Scorpion game can probably be considered an inevitability, so here's how I think they should do it: as an 8-bit parody of Mario's very first game, Donkey Kong! Scorpion would essentially be Mario, while Quan Chi would be Donkey.
Set right after Scorpion's MKA ending, when his son was resurrected, then captured by Quan Chi and taken to Hell, Scorpion pursues them with the intention of getting his son back.
Gameplay-wise, it'd be very similar to Donkey Kong, such as the sounds of squishy footsteps when Scorpion runs, but it'd also differ in some ways, beginning with none other than Scorpion's spear, of course! It'd allow him to reach upper platforms more easily, but beware all the foes and obstacles Quan Chi throws at you from the top platform, like his trademark skulls! Scorpion must reach his son in order to beat a level. Just don't throw the spear at him to do so, heh.
Scorpion Jr would look like a miniature version of his old man, but instead of screaming "HELP!!!" like Pauline in DK did, he'd scream "Get over here!!!". They could use Baby Scorpion's voice sample from MK9, as an optional feature.
Upon beating the final level, when Scorpion finally reunites with his son, Quan Chi knocks out Scorpion, nabs his son again, laughs and calls him "Bonehead". I think that insult should appear right above Quan Chi's head, no voice acting besides the laughter, just Quan Chi smiling dickishly.
Such a game could also just be an unlockable feature in a more serious entry, but this being marketed as THE Scorpion game would be much funnier, imo.