Fantastic story! I wish the older little girl had been a boy. I normally only watch or read girl on girl if a boy is also involved.
This was entertaining! I liked the premise, and how it plays on a real-life concept and takes it to a naughty direction (which is especially exciting), where it can't be taken in real life. Even the sex game shows from Japan don't go this far, in that all the contestants are of legal age.
I hope you can make more chapters of this, and have contestants in the game that can be younger (or older if you can work with it), and even have more things for the contestants to do on the show. I just like that you can write a concept like this to be believable, and it's entertaining to see where the game goes depending on the rules (and I hope you add more rules to the game in more chapters).
I'm also curious about other stories you can write set in this universe, a universe like our own but with more perverted rules and ideals. I like to see what other real-life concepts you'll explore and spice up.
The one thing I wish you should add is proper descriptions of all the contestants that includes their name, age and gender, so that I don't miss an important detail when I'm imagining them going at it.
Overall, and entertaining and exciting exploration of a game show with taboo concepts being implemented: a 4 out of 5 stars from me!