Black Box — free browser game

Four atoms are randomly placed inside an 8×8 dark box — you cannot see them directly. Click any of the 32 ports on the four edges to send a straight ray inwards. The ray follows these rules: if the cell in front contains an atom, it's absorbed (H, hit); if a single diagonal neighbour of that cell contains an atom, the ray deflects 90° away from it; if both diagonal neighbours hold atoms, the ray reverses on the spot; if an atom sits next to the entry cell on either side, the ray bounces straight back through the entry port (R, reflection). If the ray exits, both its entry and exit ports get the same letter — that pair marks 'one ray connects these two doors'. Each shot counts as one point. Mark where you think the atoms are by clicking interior cells (click again to erase). Once exactly 4 marks are placed, the 'Solve' button activates; on a correct guess the round ends and your shot count is saved — try again for a lower best. On a wrong guess the true atoms are revealed and your wrong marks turn red; from there start a new round (R) or adjust your marks. Tip: open with one ray from every port on a single edge — paired exits (two ports sharing a letter) instantly reveal deflection geometry; H/R markers pin atoms down to just a handful of cells.