Reflex

Reflex is a reaction tester. A telegraph bar fills, the screen flashes red, and you press any key as fast as you can. Your time appears with a verdict — Lightning, Quick, OK, or Slow.

Every game so far has waited politely while you typed. INPUT stops the program dead until you press Enter — fine for a question, useless for a reaction test. Reflex has to watch the keyboard while the program keeps running. That is the one genuinely new idea here: INKEY$, the Spectrum's real-time input. Meet BASIC held it back on purpose — it only earns its keep in a game like this one.

Everything else, you already have. You drew with PLOT and DRAW in Meet BASIC; here they build a bar that fills with suspense. You changed PAPER and rang BEEP there too; here they become a signal you react to. Reflex is where those pieces stop being demonstrations and start being a game.

What you will build:

• INKEY$ — polling the keyboard without stopping the program (the new core)
• A loop counter that measures reaction time — lower is faster
• A colour-coded verdict, from Lightning to Slow
• A telegraph bar that fills to a random length — PLOT/DRAW as suspense
• A red PAPER flash that fires the round, with sound on every beat
• The design concept: real-time input — the program reacts to you, live

6 units. About 4–6 hours. This builds on Meet BASIC — start there if you haven't.