Space players have the most of the thing for the creation of the new universe, i.e. the forge on their player planet and the quest to find the genesis frog, then why do Time players are necessary also? Is it because they have the Scratch construct on their player planet?

Given the Scratch is not necessary, no. I’ve thought about this with some friends for a long time and we’ve come to the conclusion that. They’re just correctors of the Timeline. Without Time Players, you have one chance to complete the game in time and close all the time loops it throws at you. Without being able to hop back and forth in the timeline and fix things, winning is nigh impossible.