That's default minigame, which is different and is an add-on. A Dedicated minigame lasts indefinitely on a dedicated server until it closes or is ended manually. There are currently (I believe) no fully functional or publicly available add-ons for this. The closest you could do would be to start a server with the "builder mode" add-on, and when you have to leave, "remove" yourself with Builder Mode. Leave the computer and Blockland running, and it could work.