(This is a blog I worked on, it's not really a story, it's a theory of mine how things would end after Jak 3. I'm also terrible at writing theories) ( A small Fanfiction "story" if you can call it one)
After Jak 3
Seem looked at Jak and asked him to follow her to the Monk Temple. Jak went there without Daxter; he stayed with Tess and went on a "city trip" trough Spargus City, because she never saw it before. Jak went with the Dune Hopper to the Temple, where he met all the Monks of the Temple itself. They were doing some kind of weird ritual with Light Eco. Seem told me the Precursors had left a gift behind for Jak, which he would get after the ritual was over. It took about 2 hours before it was over, and Jak was already asleep. Seem screamed in Jak's ear and woke him up. Jak, still tired, asked what the gift was, and Seem told him to walk into the Light. So did Jak, and suddenly he became Light Jak and he noticed he was able to stay in that form forever: he gained Unlimited Light Jak powers (I know, it comes from the game as a cheat). Jak flew around the Temple to test his new powers, but Seem said to stop and to go to Spargus City to meet again with Daxter. Jak went immediately into his Dune Hopper and went to Spargus.
Daxter showed Tess the whole city, and even his favourite place: Damas' pool in the Palace. When Jak returned they were still in the Palace and Jak told Daxter to come with him to Sig, because he would grant Jak another gift for saving the World. Jak liked this gift the most. Sig gave Jak upgrades to his Morph Gun and now he was able to shoot forever, so he had Unlimited Ammo (Also a cheat from the game). Sig told him to go back to Metal Head Tower, for another reward. Jak was suprised he had to go there, because it was all destroyed and full of Dark Makers.
When they finally reached it, they had to fight again their way to the top, but that wasn't a problem anymore with the Unlimited Ammo. They saw that there were a lot more Dark Makers then before, and all of them were at the top. When Jak defeated them all, he finally saw why they were at the top: they were defending a huge Dark Crystal. Jak was brave enough to touch it and felt the Dark Eco even more then before. Daxter understood it: He gained Unlimited Dark Jak powers (all of the three gifts he had were based on cheats in the game, I know).
End of War
With Jak's powers he was able to place some Super Nova Detonators (I know it doesn't exist) on the KG factory, which led to a victory on the KG and thus the destruction of them. The Metal Heads though, were a bit harder to destroy. The Freedom Leaugue wasn't able to enter Metal Head City because there were poisoned gasses that killed every living organism except Metal Heads themselves, so they recruited back the Hellcat Cruiser and led a Bomb Assault. Each Hellcat Cruiser was equiped with 20 Plasmite Bombs and they would explode when they touched ground. The Metal Head City was destroyed after an assault and all the Metal Heads died, who were defending the City. After that there was finally peace in Haven City.
This is how my theory would look like if there was no Jak X or Jak : The Lost Frontier. Thank you for reading this. :)
I re-made my story, so I'll post the new one.