God, trying to sum up Penance... honestly its a bit like this. Picture the most creative and odd d&d group you've ever played with. Got it? Okay. Now, remember all those times someone made a ridiculous suggestion or plan and everyone got a huge laugh out of it, the DM made a few jokes about the possible outcomes such a ridiculous decision could have, and then the laughter died down and your DM finished with "Yeah, no, your can't do that unfortunately." and everyone moved on? Penance is the result you get when your DM simply agrees when those moments happen. Its hilarious, dark, comical, insane, dramatic, immersive, and incredibly unpredictable. And honest to God, you'll love every second of it.