Update (June 2020)
Added 2020-06-05 11:49:20 +0000 UTC
Hello, guys. Here is another update about the state of the development.
I’ve finished a corporal punishment minigame. Well, it’s not exactly finished but the basic systems are working. I can build on top of that and add new features later.

That’s how it looks like. Player uses the mouse to control a spanking tool (a leather paddle). A slave reacts to strokes depending on a body part that was hit and a force. Her skin becomes red where it was hit the most. And she can start crying. It includes tears and running mascara (I also added a similar crying mechanic to vaginal sex training).
I am really pleased with how it turned out. But there are still things that I want to add in the future like:
1. Additional tools (cane, whip, wooden paddle)
2. Ability to gag the girl
3. Automatic spanking
Other things that I implemented in the game:
1. Smooth transitions between scenes
2. Some sounds
3. When training or discipline session is finished, the slave appears nude. And if she was crying, you can see the signs of that.
All the mechanics are ready for a first alpha version. I just need to finish writing some dialogues and do more testing. I hope to release that version by the end of June.