https://www.polygon.com/2019/2/4/18211246/apex-legends-titanfall-3-respawn-entertainment

Apex Legends was born out of a previous plan to make Titanfall 3, a game that is (for now) not in development. Respawn’s new battle royale game is set in the Titanfall universe, but does not include Titans, which are giant combat mechs — and a major part of the franchise. We spoke to Respawn execs about the decisions that led to Apex Legends, which was released today.

Respawn had been working on a version of Titanfall 3 at some point, but the success of PlayerUnknown’s Battlegrounds, and the company’s acquisition by Electronic Arts, caused a rethink. According to executive producer Drew McCoy, Respawn had been playing with various player-versus-player modes using assets from Titanfall 2.