Limbo is a special universe often seen as the "Playground of Gods".
Limbo is a malleable universe, as vast or as simple as one makes it to be. Limbo is based only on the rules set by its cosmic patron. There can be only one patron at any given time and that patron essentially is God for that universe for as long as it chooses to be.
Limbo can be put under the control of any sentient being, including the simplistic of forms. This has led to unusual stories of children being given the power of gods to see what they would do with such power. Quite often these "experiments" would end up with disastrous results, and the child-god would be coerced to relinquish their power.
Limbo has also been the place for negotiations between cosmic entities. The rift between Olympian and Roman Gods was settled in Limbo. Likewise the conflict between Norse and Teutonic Gods was finally settled in Limbo, which was then called Ragnarök.