Jak and Daxters world is one filled with monsters known as Lurkers, a mystical energy called Eco and ancient technology left by an ancient race only known as the Precursors.
This is the story of Jak (Left) and Daxter (Middle and Right), as I mentioned their world is filled with an energy called Eco. And do to an accident Daxter was transformed from a human into an ottsel after coming into contact with dark Eco.
There are several different types of eco.
All coming in a different color.
And providing a different power.
But in Daxter case however touching dark Eco mutated him into a new form.
Jak and Daxter needed to travel their world in order to find the sage of dark Eco Gol (Bottom Right) to help Daxter. They needed to find the other missing sages along the way as instructed by Samos the sage of green Eco (Top Left).
With the help of their friend Keira and the Zoomer (Top Right) she built, powered by the ancient energy source known as Power cells (Bottom left), Jak and Daxter were able to travel to their destination through normally impassable obstacles.
Upon reaching the end of their journey Jak and Daxter find out that it was actually Gol, the dark Eco sage they were searching for to change Daxter back into a human, and his sister Maia that had kidnapped the other sages. Gol and Maia had kidnapped the other sages in order to power a large precursor robot in order to unleash dark Eco upon the world so that they could reshape it to their liking.
And with one final fight against Gol and Maia in their precursor robot. With Daxter giving up the light Eco (the only thing that might've been able to change him back) created during the fight to Jak, Jak was able to defeat Gol and Maia once and for all, and Saving their world.