Add Playground Mode to main screen where you can choose Battle Royale and Save the World modes.

Also change mode's mechanics. Make time and resources unlimited.

Make enough space for ~10 people. Make team change overhaul.

Make spawn points editable. Remove weapon drops after death.

Make setting menu for all of this if somebody wants to disable/enable certain mechanics.

This is the real playground.

If playground mode is permanent why not make it a Battle Royale, Save the World-like mode?