Good news, Bub Block finally has official online support! This comes with a HUGE caveat, however, as the online mode in its current form is still very buggy and limited. If the Remote Play Together feature was already working great for you, then I would recommend sticking with that. But if you want to try out the new, "proper" online mode, here are the details:

• In the game rules screen, select the Invite button to invite Steam friends to play with you.
  
• There are currently no public lobbies; you must play through Steam invites.
  
• Online players will have a Wi-Fi icon next to their Bub avatar to denote that they are not local players.
  
• Multiple people can be on the same computer and still play online.
  

If you run into any issues, please post them in the Steam forum so we can investigate. Thank you!