This is a smaller, targeted update designed to move actual games into sandbox play.
Rescue from Crisis: If your overflowing neighborhood can no longer be saved through crisis management you can now transition that game directly into Sandbox Mode. This allows you to grant yourself infinite inventory to untangle the mess, experiment with solutions, and see what could have been.
Post-Game Continuation: Sometimes there was no crisis, perhaps you were victorious! You can now take completed games out of the post-game review screen and continue straight into the Sandbox. There's no scoring that will be recorded from the sandbox but it might help you to discover more about the city that you built.
Reminder: As introduced in v6.15, any game transitioned into Sandbox Mode will be permanently watermarked. You can save and continue these cities, but they will not record additional score or affect your leaderboard standings.