Edit: Since lobbies are going "byebye" I had to edit this lol
It works like this: Advertisement boards in the Overworld or Cubic Town Center, to advertise realms. like you interact with it and you see adverts there, and could pay some cubits (or re cubes) to set an amount of times your advertisement in will show.
The way advertisements would show is like this:
You pay to show your advertisement. You pay 100c to show it 20 times. So 20 people can see the advertisement for 2hrs. One person can see it infinite times for 2hr to keep people from spam seeing your advertisements away.
The advertisements could be like an auto generated image of your realm with a caption saying: Checkout "realm name!"
there could be multiple advertisements boards with randomly selected advertisements in the overworld, and maybe a few in the Town Center. The adverts change everyday.
Also, a menu to scroll through 10 ads.
So it's not chaotic, like pens, there would be multiple ads, and everyone can put up an ad at any time. Ex: Pay 200c to have 20 qbees see an your ad. These 20 qbees are the only ones seeing the ad. When they go to the bulletin board, they see that ad, plus 9 others.
To prevent people from spamming their own advertisements, you can only have one advertisement every 3 days. You could only advertise one realm at a time.
So in short, there will be bulliten boards in the overworld and Town Center, with 10 random ads on each that will have 10 random ads on each board all day. You pay c or rc to set an amount of players that see those ads all day.
Edit: you would also need to be at least level 15 to prevent spam
Sorry that this is long... I just wanted to get my idea out there :)