There was a livestream for the Super Robot Wars series on 18th March, with Super Robot Wars DD and Super Robot Wars T being in it. In the livesteam, we get to see new gameplay along with how the whole world switching works.
We previously had an interview with the producer, Masatoshi Akai and series producer, Takanobu Terada. They mentioned that by featuring 4 worlds will allow players from different era to enjoy the game together. So, the story chapters will vary differently from each of the 4 worlds. In the livesteam, we can see that by completing a chapter, players will have to go through 5 checkpoints. Moreover, Bandai Namco confirmed that units acquired in other worlds can be brought into the stages.
To switch between worlds, all players have to do is go to the Story menu and switch it there but if players were to switch it while their story chapter is in progress, they may lose it.
Check out the livestream down below (gameplay starts at 9:13):
The game was set to launch for iOS and Android in Summer 2019 but due to some issues, they will delay it to Fall 2019.
Source: Siliconera