• ✓Idea: blood-group genetics should play like a detective puzzle
• ✓A three-panel lesson first: the three alleles → the genotype table → a Punnett square (skippable)
• ✓Real notation throughout: ii = O, IᴬIᴬ/Iᴬi = A, IᴮIᴮ/Iᴮi = B, IᴬIᴮ = AB
• ✓Question 1 — four children (A, B, AB, O): which one could be theirs?
• ✓Question 2, taking turns — four men: which could be the father (mother's genotype + child's group given)?
• ✓Puzzles are generated from the Punnett square itself, and only ones with a single answer are used
• ✓A wrong pick quietly crosses that person out and explains the genetics — never a buzzer
• ✓Every explanation is computed from the data, so it can never contradict its own puzzle
• ✓Two rule-outs (or the hint button) opens the real Punnett square
• ✓A run of misses across a round opens a breathing pause; Delphi hosts
• ✓Everyone on the tree is one of 24 painted Kidsquare busts, not a vector shape
• ✓Parents, both sets of grandparents, aunts, uncles and the in-laws — each question picks a different couple
• ✓The scene is a back veranda looking onto a hydrangea garden, with a tall repaint for phones
• ✓Some questions have more than one answer — Iᴬi × Iᴮi opens all four groups, and every one must be tapped
• ✓npm run verify:blood proves 32,000 puzzles mark exactly what their own Punnett square allows
• ✓Add the Rh factor (+/−) and a three-generation treeplanned

✓ = done · ☐ = planned. Every game is built one step at a time like this.