Frak! — browser JavaScript port

Stage 4.7 parity build · BBC MOS pitch/envelope semantics · original left/right attract transitions · Stage 2.1 gameplay retained · explicit 6502→JS mapping

Level
Transform cycle
Player
Time
Object queues
Score
Lives

Original controls: Z left, X right, ' up/jump, / down, RETURN yo-yo. Arrow keys are convenience aliases; Space aliases RETURN during play and starts from the title.

Other original-style controls: Q sound off, S sound on, Delete freeze, C continue, Escape return to title. Debug/navigation: 1/2/3 select A/B/C; [/] change transform.

Stage 4.7 scope: gameplay remains unchanged from the validated Stage 2.1/3 path. Sound now uses the BBC MOS pitch lookup, 100 Hz ENVELOPE state and SN76489 attenuation model, while Web Audio remains the final square-wave output. The attract screen runs the recovered 31-frame left/right transitions and final Trogg sequence. Title, cast and high-score text uses a fixed BBC 8×8 bitmap renderer. Stage 4.7 also matches the reference title-panel geometry, suppresses leading score zeroes like PrintPackedBCD, and keeps Trogg visible when the final FRAK! bubble is overlaid. Browsers require a user gesture before audio can become audible.