There are now 2 different types of prison servers, which kind are you wanting?
The Classic - with contraband weapons, guards, and you have to move into pvp areas to get to the shop. Shop plots would cost in game cash per week, Prison cells that lasted for a week before you had to rebuy (or your stuff could be lost to whoever bought your cell)
The New- You get tp'd to a mine and you just mine, no fall damage and you have an OP pick. Rank up with cash and shops are @ the mine. No pvp unless you're in a pvp mine. Guards aren't necessary and donor / vote mines are available. Plots are free etc.
~ @SX1
I used to play what you call classic, back in 2012. It had a huge black market of weapons armor and potions as such as they were illegal in the prison. I remember as a noob scraping together enough cash to get a small cell, and then taking some days to make some insta damage 2 potions. Then when some others were fighting I ran in with 9 insta damage 2 potions and got all of their stuff :3
From there on out I started renting a whole plot, and made a hidden basement where I ran a brewery.
Some months later I was basically one of the so called kingpins, but then the guards ransacked my plot and found the button to my basement. They took all my stuff and sentenced me to 45 minutes in jail. (You may be wondering, a jail within a jail? Yeah, basically a 1x1 cell only made of iron bars and out in the open so all could see you and approach you, and when you were in that cell you were also /muted)
It was so much fun.
Anyway, I don't think it'd ever work on Meep. Most of our playerbase is young, and one of the key things about a prison server is no chat rules at all.
I would love a classic prison gamemode, but not on Meep.
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