The game made for single player only, multiplayer needs alot of coding, multiplayer will have cheater and hacker and did you know, the game made from one creator that doesn't have a big company . BUT in my opinion the game will never single player only forever
He just want to make the game easy to access and I think the multiplayer will be in a future update (not less than 6 month). Maybe if you are open the game it not using a internet connection unless you press the multiplayer button from the main menu (my opinion)