Your intuition is correct in that this の is the same as the の in 兄の佐藤.
Similarly to the explanation in the similar question How does the の work in 「日本人の知らない日本語」? 全世界注目の is a relative clause that is modifying the noun セルゲーム.
の can be replaced in these sentences by である. In the sentence you are asking about it can also be replaced with な but not in the sentence about your brother Sato.
兄である佐藤
兄の佐藤
[全世界注目である] [地球の運命を賭けた]セルゲームが始まろうとしています。
[全世界注目な] [地球の運命を賭けた]セルゲームが始まろうとしています。
[全世界注目の] [地球の運命を賭けた]セルゲームが始まろうとしています。
A pretty good example of this rule is here: http://www.japaneseprofessor.com/lessons/beginning/modifying-particle-no/
The relevant part is:
まほうの とびら mahou no tobira a magical door
Mahou (magic) is a noun, but it's being used like the adjective magical, which doesn't >exist in Japanese. And while "mahou no hon" could be "a book of magic" (filled with >spells) or "a magic book" (itself enchanted), the "of" interpretation for no does not >exist in every case. So while "of" is a possible translation of no, it's not always the >best translation.