How can I transition from a normal build to the "Blockheads Ruin Xmas" Gamemode?

[Poliwhirl]

I couldn't word exactly what I need help with in the title, but basically I'm gonna try to set up a Christmas server (not now but later), and I want there to be a lobby thing where people can just hang out and listen to some cool Christmas Music. However, I also want it to intermittently begin a game of Blockheads Ruin Xmas, almost like those Deathcube/Falling tiles servers, if that makes sense. Maybe even make it optional to join. Would anybody know how to do that? Should I ask Modification Help?

[Ad Bot]

[Nix the Glaceon]

add a teledoor that actually leads from the lobby to the main build, add the lobby away from the main build.

[Conan]

admin menu: change gamemode > christmas gamemode.

make your lobby its own gamemode and change back between rounds