Prison Architect's latest update lets you control your prison warden, and that small change has a massive impact on the way you play. Rather than the normal all-seeing viewpoint, the whole map is covered by a fog of war, save for whatever your warden would be able to see with their own two eyes. Anything around a corner is hidden and can't be interacted with, so if you want to upgrade your maximum security wing you're going to have to walk there first. Gulp.
You WASD around the prison and can pick up objects, including weapons and body armour to protect yourself from inmate attack, which seems almost inevitable. If you don't want to get your hands dirty then you can recruit guards to your personal protection squad. They'll keep you safe but cost more money.
I think it's a really clever addition. It will inevitably lead to slower expansion because you'll be constantly wary of getting injured, and you can turn on permadeath mode if you want to ramp up the difficulty even higher.
Elsewhere, the update adds floor signage, which is a handy way to direct prisoners and staff down particular paths and control foot traffic. They'll follow the directions unless there's a much quicker way to get where they're going.
You can read the full change log, including lists of bug fixes and balance updates, here.