The rule kittens cannot work out for themselves
A kitten does not distinguish between the finger game you enjoyed when she weighed very little and the bite you object to when she is a strong adolescent; to her, it was always the same game with the same rules. So the rule has to live on the human side: hands are for stroking, feeding and care, and they never wiggle, pounce or wrestle. Every game runs through an intermediary, a wand, a kicker toy, a ball, a feather on a string. That single consistent boundary, kept by everyone, is what produces an adult cat whose play stays on toys even when she is excited, because she has literally never practised the alternative.
Play like prey, not like a wrestling partner
Good toy play imitates a hunt in miniature. Move the toy away from the kitten rather than at her face, let it hide behind furniture legs, freeze it, then make it dart and tremble. Allow regular catches, since a kitten who never wins loses interest or becomes frustrated, and frustration is a biting trigger in its own right. Finish sessions with a final catch followed by a small meal or treat, completing the hunt-eat pattern and leaving her satisfied rather than wired. Sessions of a few energetic minutes, several times a day, suit a kitten far better than one marathon that pushes her past excitement into overstimulation, which is where most play biting actually happens.
Read arousal and pause before the bite
Biting in play is usually the last step of a visible build-up. The tail starts to lash rather than wave, the ears turn, the pupils widen, the body goes still for a beat, and the kitten may fix on the nearest moving thing, which is often your hand withdrawing the toy. Learn your kitten's particular sequence and treat its early stages as a pause signal: freeze the toy, let the tension drain, then either resume more calmly or end the session with a treat. Children need this taught explicitly, because their instinct is to snatch a hand away at speed, and a fast-retreating hand is the most prey-like object in the room.
When teeth do meet skin
It will happen occasionally even in careful households, and the response matters more than the incident. Go still, stop the game, and withdraw attention for half a minute or so, without shouting, spraying or pushing the kitten away, all of which read as either play escalation or frightening unpredictability. Then offer the correct target, a kicker toy she can grab and rabbit-kick to her heart's content. If biting is frequent despite toy-based play, look at the whole picture: too little play overall, sessions that run too long, or handling that overstimulates her beforehand are the usual causes, and each has a straightforward fix once identified.
The whole household plays by the same rule
One person who secretly plays the finger game because it is funny will keep the habit alive against everyone else's work, and the kitten will simply learn which human is a legal target. Agree the no-hands rule, the pause signal and the correct response to a bite as household policy, and include it in the instructions for anyone who plays with her. KinsLe Care Teams supports that consistency by assigning the daily play sessions as named duties, so the kitten gets her games on schedule and every player handles them the same way.