We don’t know anything about it, except that it’s more Spelunky.
Image courtesy of Mossmouth
It's been a long time since game designer Derek Yu announced a new game— Spelunky was released in 2012, itself an update for the original Spelunky game, released in 2008. It wouldn't have been shocking if Yu was ready to leave Spelunky behind, but instead, he's headed back into the caves, with a full-fledged Spelunky 2. I'm already terrified.
The trailer at Sony's Paris Games Week event didn't show anything beyond a title.