@Dennis1980 @gorostilllives
Good points, I'll be happy to explain what I mean a little more.
First, to address what I mean by the established lore, I would probably say the main games, or at least the original timeline. Yes, there have been some changes and contradictions throughout the story - And I would say the new timeline has even more of them - but there was quite a lot that was introduced and remained consistant throughout the saga. I would also consider things from the new timeline that weren't retcons to be part of the lore; for example the real names of the Sub-Zero brothers. The things that were retcons, I think they can be more flexible with.
For example, Liu Kang being the Mortal Kombat chamption and winning the first tournament was established in MK2 and carried through all the way through MKA and into the new timeline. It was confirmed in MK2 that he earned the title by defeating Shang Tsung, and also by implication Goro (this was confirmed in Goro's MK4 bio). Therefore, I would call that a solid part of the lore, and if that's changed, then it I would consider that not really adhering to the lore. So if they have someone else kill Goro (before the tournament even officially starts), that would kind of mess up the lore. A workaround to this would be, if you wanted to focus on another character, center the conflict around their arc, but keep Liu vs Goro and Shang intact in the background.
Another example would be character origins. Let's use Kabal for example. It was confirmed that Kabal was from earth originally. Now, if the script writers decide that they need an Outworld villain, and Kabal looks cool, so they decide to make him from Outworld in the movie - that is not really adhering to the lore. Here's a way I could accept them bending this a little bit: Maybe in this version the black dragon has ties to someone from Outworld; after all in MK3 it was established that the Black Dragon were doing some arms dealing with Outworld; maybe we see that was already getting started beforehand. Maybe Kabal had his "accident" around that time, and is saved thanks to a fusion of Outworld magic and Earthrealm technology, and in exchange he works as an enforcer of Outworld. That way you have your change, but you're staying truthful to the spirit of the character.
Another example of a character origin, Sub-Zero. It is pretty well established in MK lore that the Sub-Zero brothers are from Earthrealm (albiet with some Outworld blood, but still born in Earthrealm). It was also established that Bi-Han killed Scorpion and had his MK Mythologies quest shortly before the MK1 tournament. Therefore if they decide to make Sub-Zero a native Outworlder, who killed Scoprion hundreds of years ago, that is not staying true to the lore. A Here's a workaround if they want Sub-Zero working for Outworld: Sub-Zero's clan is not very honorable, and they'd be happy to work for whoever pays them well; in exchange for a bunch of money and a good place in Kahn's empire, they send Sub-Zero to work for Outworld. Again, that's a change that will let them put the character where they want to, but still stays true to the spirit of the character.
Those are a few examples of what I mean, and in my examples I threw in some ways could bend the lore while still at least keeping the spirit of that characters there. Everyone's mileage will vary, and some people may not be okay with even that, but at least they, as fans, could appreciate that they kept each character as true to their game counterparts as possible. But there's only so far you can bend it before it breaks. For example, in MK Legacy season 2, when they introduced Liu Kang as a villain who cusses at Kung Lao and works for Shang Tsung; that was too much of a change in my opinion.
As for what I mean by "filling in the gaps": Just by the nature of this being an adaptation of a videogame, rather than a book, comic, or other movie, there is a lot of stuff that never get shown to us. In each game, we tend to find out who comes out the champion, and maybe a few details about who fights who. The rest, is pretty much up to speculation.
For example: if we were doing a straight adaptation of MK1, here's what our rules would be. We know that there's a tournament with seven important characters: Kano, Liu Kang, Raiden, Johnny Cage, Scorpion, Sub-Zero, and Sonya. We know that there are two big bads, Shang Tsung and Goro, and we know that there is another mysterious foe lurking in the background, Reptile. We know that at the end, Liu Kang ends up beating Goro and Shang, and that at some point Scorpion kills Sub-zero, and we know that at some point Kano and Sonya end up captives to Outworld. Other than that, it is fair game for you to do what you want to with the script; you can arrange your fights however you want. You get to choose who fights who, how the fights are choreographed, what the characters do in between fights. You choose the dialogue, musical queues, the lighting, overall mood and theme of the story, and more. That's what I mean by filling in the gaps; it's something that will inevitably happen, and it's what makes a movie adaption so different than just replaying the games again (especially the earlier games that had no story modes).
