Hold Space to boost

Boost will trade reaction time for a faster finish and more valuable pickups. Holding Space doubles course progress; releasing it restores normal speed, with no fuel meter or cooldown.

The boost routine reads Space and stores 0 or 1 in boost_time. Despite that name, the byte is a held-key flag, not a duration. Main code adds one to select one or two simulation steps for this update.

The clock still measures PAL frames. Each simulation step steers, moves objects, checks contact, considers a spawn and checks completion. During boost those operations happen twice before the next outer update. The ship also responds on each step so its steering keeps pace with the accelerated course.

Preserve the intermediate position

Doubling every meteor’s movement in one addition would jump over an intermediate state. Instead, the program repeats one simulation step. After measuring the frames and calling boost, the main loop stores boost_time+1 in steps_left and reaches a new label, race_step, at the start of the ship and object work. Each pass checks for a fatal meteor contact before allowing another step or a successful finish.

At race_continue, steps_left is decremented. A nonzero value returns to race_step; zero proceeds to the HUD and then the next frame wait. A win or loss takes its result path immediately.

race_continue:
 ld a,(steps_left)
 dec a
 ld (steps_left),a
 jp nz,race_step
 call hud
 jp main_loop

This is not perfect continuous collision for arbitrarily large speeds. It preserves our existing contact checks at both of the two accepted course steps, whose speeds and collision regions have been tested together.

Make rewards use the same decision

A star contact adds boost_time+1 score units: one unit normally, two while boosting. Because units represent tens of points, the pickup is worth 10 or 20. The contact still clears the object’s kind so the star cannot score again on the second step.

Hold and release Space while watching boost_time and ticks. Elapsed should keep following real frames. The controls line at the bottom now mentions SPACE BOOST, and the HUD shows 1X or 2X. Holding Space to launch does not start the run boosted, because unit 11’s title waits for Space to be released before calling new_game. Q returns to the title; R retries a result. Starting again through the editor creates a fresh machine.

The straightforward renderer currently erases and redraws every object on both boosted steps. Play into a dense patch and inspect frame_delta. Native execution sometimes records four frames between updates instead of two. That observation is our reason to optimise drawing next; it is not a reason to stop checking the intermediate collisions.