Make each burn count

Continue with Make another attempt. Keep the same gravity, thrust strength and landing test. Change one thing: a burn now spends fuel.

Add line 90. Replace lines 70, 130, 150, 270, 370.

  70 PRINT AT 8,2;"Thrust uses fuel."
  90 PRINT AT 12,2;"Empty tank? You still coast."
 130 LET x=24: LET y=400: LET v=0: LET fuel=45: LET r=4: LET burn=0
 150 PRINT AT 0,1;"FUEL       SPEED       MAX 12"
 270 IF k$=" " AND fuel>0 THEN LET burn=1: LET fuel=fuel-1
 370 PRINT AT 0,6;fuel;"  ";AT 0,19;v;"   "

Decide whether the engine actually fires

Line 130 adds fuel=45 to the starting assignments. The engine condition now needs both a Space reading and a positive reserve. As in the menu filters, AND combines those conditions: both must be true for the rest of that line to execute.

burn still starts at zero. An accepted burn sets it to 1 and subtracts one fuel unit. Velocity and the provisional flame both use that same flag. We do not read the keyboard again to decide what picture to show.

Consider one fuel unit remaining. The condition succeeds, sets burn=1, and changes fuel to zero. That last paid-for burn still changes velocity and shows the engine. On the following update, the fuel condition fails, so burn remains zero even if Space is held.

Show the decision, not just the key

For a paper trace, start an update with y=1000, v=10, fuel=1, r=10 and a Space reading. These are prepared values, not a claim about a flight we have played. Predict burn, fuel, velocity, position and the printed character after this update and the next one, with Space still read. Neither update reaches the ground or the upper limit.

Repeat the prediction with fuel=0 at the start. Which values in the first update change, and which input reading stays the same? If the conversion to a screen row needs refreshing, revisit Make another attempt and its complete listing before altering the calculation.

The fuel number gives information beyond the flame’s colour. Ask someone to explain what happened before telling them the rule: can they distinguish an accepted burn, an unavailable burn and a finished attempt? A correct counter alone does not tell us whether the feedback is understandable.

Empty does not mean finished

Nothing here treats an empty tank as a collision. Gravity still changes velocity, position still changes, and contact still decides the outcome. A slow enough approach can coast onto the ground safely after its last burn.

The instrument row now reserves separate fields for fuel and velocity. The trailing spaces clear leftover digits when a value becomes shorter. The title explains that an empty tank still permits coasting. These changes give the player information about the rule rather than adding another penalty.

Hold Space for a whole attempt. Fuel should reach zero without becoming negative; after that the engine indicator must stop even though you keep holding the key. The craft eventually falls. Retry should restore all 45 units as well as position and velocity.

For a short boundary experiment, save your ordinary version, then change the starting values in line 130 to position 1899, velocity 0, fuel 0 and row 18. Run without thrust. Gravity changes velocity to 2 and proposes position 1901; contact clamps it to 1900, producing a safe coast. This is a deliberately prepared test, not a claimed successful approach from the normal start. Restore the original line afterwards.

Keep practising with the normal start. Using less fuel is useful only if the approach remains controllable. We have not added a fuel-efficiency score or changed the safe-speed limit.

  10 BORDER 0: PAPER 0: INK 7: BRIGHT 1: CLS
  50 PRINT AT 3,9;"TOUCHDOWN"
  60 PRINT AT 6,2;"SPACE: brake your fall"
  70 PRINT AT 8,2;"Thrust uses fuel."
  80 PRINT AT 10,2;"Safe speed: 0 to 12"
  90 PRINT AT 12,2;"Empty tank? You still coast."
 100 PRINT AT 15,2;"S launches. Q quits."
 110 GO SUB 800: IF k$="q" THEN GO TO 850
 120 CLS : GO SUB 600
 130 LET x=24: LET y=400: LET v=0: LET fuel=45: LET r=4: LET burn=0
 140 PRINT AT r,x;"A"
 150 PRINT AT 0,1;"FUEL       SPEED       MAX 12"
 160 PRINT AT 1,1;"SPACE THRUST  Q QUIT"
 200 LET k$=INKEY$: IF k$="q" THEN GO TO 850
 260 LET burn=0
 270 IF k$=" " AND fuel>0 THEN LET burn=1: LET fuel=fuel-1
 280 LET v=v+2-6*burn
 290 IF v>60 THEN LET v=60
 300 IF v<-30 THEN LET v=-30
 310 LET ny=y+v: LET contact=0: LET limit=1900
 330 IF ny>=limit THEN LET contact=1
 340 IF contact=1 THEN LET ny=limit
 350 IF ny<300 THEN LET ny=300: LET v=0
 360 LET nr=INT (ny/100)
 370 PRINT AT 0,6;fuel;"  ";AT 0,19;v;"   "
 375 LET a$="A": IF burn=1 THEN LET a$="*"
 380 PRINT AT r,x;" ";AT nr,x;a$
 390 LET y=ny: LET r=nr
 400 IF contact=1 THEN GO TO 700
 410 PAUSE 2: GO TO 200
 600 FOR c=0 TO 31
 610 FOR j=20 TO 21: PRINT PAPER 4; INK 0;AT j,c;" ";: NEXT j
 620 PRINT PAPER 4; INK 0;AT 20,c;"#"
 630 NEXT c
 650 RETURN
 700 PRINT AT r,x;"A"
 710 LET m$="Too fast!"
 720 IF v>=0 THEN IF v<=12 THEN LET m$="Safe landing!"
 740 PRINT AT 2,1;m$;"    "
 770 PRINT AT 1,1;"R retries. Q quits.            "
 780 IF INKEY$<>"" THEN GO TO 780
 790 LET k$=INKEY$: IF k$<>"r" AND k$<>"q" THEN GO TO 790
 795 IF INKEY$<>"" THEN GO TO 795
 796 IF k$="q" THEN GO TO 850
 797 GO TO 120
 800 IF INKEY$<>"" THEN GO TO 800
 810 LET k$=INKEY$: IF k$<>"s" AND k$<>"q" THEN GO TO 810
 820 IF INKEY$<>"" THEN GO TO 820
 830 RETURN
 850 IF INKEY$<>"" THEN GO TO 850
 860 PAPER 0: INK 7: CLS : PRINT "Finished.": STOP