The Pen MC is a classic prison server that feels like the old 2014 style. It is barebones and all about grinding your way up instead of getting overpowered gear fast.
You mine and you smelt ores yourself. Selling is not free money because you have to move through pvp areas and actually survive to cash out. The whole point is that progress takes time.
After you rank up through A to H you can reach Parole and then keep going with a prestige system. You are not stuck doing only one thing either. You can focus on mining or try custom fishing to make money or jump into a mob arena with waves and boss fights.
There is also a cookie farming bakery system where you grow wheat and cocoa then bake cookies with custom mechanics. It has long term quests and leaderboards and you can trade baked cookies into higher tier rewards.
The server has guards and contraband rules plus illegal crops for high risk high reward. You can rent cells and plots use an auction house do bounties try parkour challenges and run player shops. It also tries to avoid pay to win because premium stuff can be earned through gameplay.
