Anyways, here's another analysis of a world (W4)...
World 4 (aka 450 million B.C) is set in the trio's universe and timeline, taking place 450 million years before the events of Help Wanted and moments after the Squidward from SB-129 was ejected out of the universe and into the Space Time Continuum.
Because of this, Primitive Sponge and Star still have the experience of Squidward's bad music and when they see him they chase after him...
You basically play as Squidward during this time, where you have to run during the first encounter with the Primitives and hide from them and avoid them from spotting you for the second and third encounters.
Ultimately Spongebob and Patrick find Squidward and ultamatly pacify their primitive doablegangers, reassure them that Squidward was safe and he meant no harm.
During this time Spongebob, Patrick, and Squidward search around the prehistoric landscapes of what will become Bikini Bottom and after defeating mid boss Zapper (built to fight better in the prehistoric landscapes/seascapes), they receive a message from Plankton stating that he has built a base not long before they showed up by manipulating time to slow down so that no one would notice.
Plankton was well aware about SB-129 Squidward traveling back to that point and wanted to use the advantage of the Primitives being angered by Squidward to possibly kill him off, though if this did not succeed Plankton would utilize a base that he built within the time in which no one was around to possibly stop him from manipulating time to slow down...
Plankton would then give the directions to the trio to his base, in which he plans on killing them in past and ultimately go back to the present utilizing prehistoric creatures to conquer Bikini Bottom and Atoll area.
Now I'm going to skip to when Plankton gets defeated, as when he does he ultimately utilized the manipulation of time where if the base ultimately gets critically damaged before it served its purpose it'll erase everything that been altered but at the cost of beings that don't belong in that time period.
Plankton last resort, basically leaving behind and erasing the trio from existing. Ultimately the trio runs and jumps on Plankton's Personal Fish-Sized Robot Cruiser just as Plankton activated time travel, thus traveling to the next world (1.999 million B.C) and escaping erasure from existence...