- Full chess rules engine (legal moves, check/checkmate, castling, en passant, pawn promotion)
- Board rendering, piece placement, and move highlights — all drawn programmatically via Node scripts
- Breathing aura on selected pieces with contour-following particles
- Smash knockout effect on captures — pieces launch off-screen with spin, speed lines, and impact flash
- Rainbow bubble path effect for notifications — 7 color layers of particles that assemble along text stroke paths, then disperse with wind