CrossCode got a pretty big update today with the new arena. The Rhombus Square Arena is a boss rush mode with a few different levels of difficulty so you can put your character and combat skills to the test. There are 3 different difficulty levels that will change the enemies from regular baddies up to temple bosses if you're feeling up to it.
They've also added a couple new quests which you can pickup at the bulletin board, an improved S-Rank mode, and several new NPCs scattered throughout the game.
Most importantly though, are the pets. Not much information is given about pets at the moment other than they will follow you around and look cute. You can also give them a pat on the head to show your affection.
Head over to Radical Fish Games' official page
for a bit more information.