Advance credit to the creditworthy, who must pay it back but can usefully produce with it meantime.
Define production as, for example:
Impose in the game structure the feature that creativity itself requires spending in the space. But you can borrow that in game money in order to produce, i.e., to put that product into the space. Instance reuse having a cost that the producer must pay for, for the privilege that the user must then pay extra for, so that the in-game central bank will get its loan paid back. Like a resource cost, or a cost of production.
Then you need a place to spend it. On advertising. On admission tickets for your own direct consumption. On a cash exchange market.
Give a UBI to participants to support a consumption economy. Provide for bankruptcy, too, though; or let folks buy in on the cash exchange market.