Being able to take an item out of one game and move it into another game sounds like fun but keeping track of the ownership is a tiny problem compared to having the appropriate assets to draw the objects cross-game never mind implement the attributes of the objects. (And not let imported object "break the game")

If you had it all in a unitary system like the OASIS from Ready Player One it might be possible but unless all the games are under the same framework it would take a lot of coordination.