Sea of Stars has two endings, but there’s not that much difference between the two.

In the most common one, the party faces up against Erlina, transformed into a champion of the Fleshmancer. Once they defeat her, both Zale and Valere ascend to face off against the World Eater.

In the secret ending, the party manages to travel back in time and save Garl, thanks to Rashan’s powers and B’st’s abilities. Now, the final confrontation has Garl taunt the Fleshmancer, making him not summon Erlina but face the group himself.

You can only get the second ending after the first one, and it involves completing all the tasks in the game, like collecting all the rainbow conches.

This ending still has the Solstice Warriors ascending to fight the World Eater, with the biggest difference being that now you see an elderly Garl during the ending as well.

You see him, Teaks and the Artificer look after an altar meant for the ascended Solstice Warriors.

The real meaning of the ending is that it works as a prequel to The Messenger, Sabotage Studio’s previous game. There are plenty of references in Sea of Stars to The Messenger, particularly the altar during the ending cutscene.

That altar is what the titular Messenger uses to contact the previous godly heroes, and it looks just the same in both games.

Other connections include the Artificer, the merchant of the Messenger, and Brugraves, whose demonic visage is seen during the secret ending of Sea of Stars, and looks like a boss fight of The Messenger.

The heroes the Messenger contacts are clearly Zale and Valere.

This means that the events of Sea of Stars are just one of the confrontations between Rashan and Aephorel, the Fleshmancer.

They continue their confrontations far into the future, into the world depicted in The Messenger.