ex: start at one point and eventually end at that starting point
are you looking to make it a actual sphere? or just seem like it is?
if you want an actual sphere with gravity id check out the plugin and video by unreal tefel. he made a system where you can make planets in blueprint, though you did tag this as c++ so you could always make your own solution.
if you wanted the game to appear to loop without being a sphere you would always use streaming levels. this way you could just have a few levels transition back and forth. or you could always come up with a clever transport system to move the players character without them noticing.
Make it seem like it. Like I’m going to make it flat but I want it to eventually making it to where you end back to where you left. So if you leave you house and keep walking straight after an hour you will walking up behind your house.
Just teleport the player pawn at the back of the house…
Say if the world position X>500 teleport at (X - 1000, Y) and if the Y > 500 teleport at ( X, Y - 1000 ).
Make the same if X < -500 and Y< -500 and you will be able to wrap a 1000/1000 square.
If you copy your 1000/1000 patch 9 times in a square and add some fog in the distance, the player should not notice the difference.