Drift
Spectrum · BASIC
Turn, thrust and bring a drifting ship gently into dock
9 units
The nose points one way. The ship travels another. Your job is to make those two facts work together long enough to reach the dock gently.
Use O/P to turn anticlockwise or clockwise and SPACE to thrust. Release thrust and the ship keeps drifting. To slow down, turn against the motion and burn again. DOCK OK means the speed is low enough; the ship must also be inside the docking region. R retries, Q quits and S starts from the title.
Drift runs in Sinclair BASIC on a stock 48K ZX Spectrum. It is silent, with eight headings and a single docking challenge. Turning and thrust are separate actions. The speed and directional readouts help you judge motion that can be hard to see in a small triangle.
A nose is not a velocity
We begin a new program with three lines around a centre. A table of eight directions lets the shape turn; thrust then changes its velocity. Braking follows from those same rules. Later we expose the motion in a readout and combine position with speed to decide whether an arrival counts.
Each lesson explains the BASIC it uses. The finished source grows through seven runnable checkpoints across nine lessons: the braking experiment and the saving lesson reuse programs that already work. Lessons 7 and 8 add opening instructions and save a tape that starts in a fresh machine. The last lesson stops the still ship flickering by redrawing it only when its picture changes.