How it should look:
He’s a lucid dreamer; he has been ever since he was a little boy. He has visited many worlds and can do anything there, but he doesn’t know that all of these places are real, and he is making a big impact in many of them.
Why it should look that way:
The doubled r at the end of dreamer is clearly a typo.
Change the comma after dreamer to either a period or a semicolon; if you use a semicolon, don’t capitalize he.
He has visited so many worlds that what? Either add something to this sentence after worlds or delete so.
Add a comma after worlds (or whatever you decide to add into the sentence following that word).
Ending both parts of this compound sentence with the same word (worlds) makes it sound a bit clunky. (Yes, really: It sounds to me as if the sentence is making a sort of dull, flat thud at the end. Or it moves awkwardly. Or something. The trouble with even extremely mild synesthesia is that there’s no standardized language for describing it… and now I’ve gone and unintentionally compared myself to that other guy again. *sigh* At least I’ve got a handy semi-quote from one of his “book-cousins” for describing how the lack of ways to describe an idea feels, right?) Consider replacing one worlds with a pronoun or a different noun.
Add a comma after real because the sentence is compound.