Note: If you own the game on Steam, you need to opt-in to the Beta branch to be able to play Update 13. You can find the update video below:
Actually being in your own prison, adds a whole new and interesting way to play the game. You have to keep an eye out, since prisoners could end up taking you down. You can't just attack anyone you like of course, since this is a legal establishment. However, if attacked yourself you're able to defend yourself with various armaments. You can even recruit your very own guard squad, they aren't cheap though.
There's even a Permadeath option, for those who really like a challenge. Find the full release notes here. Really do love this game, fantastic to see that Introversion continue to update it so long after release!
GOG links are affiliate links.