10 REM ========================================================================
=
20 REM           JUPITER LANDER 1:1 REMAKE - ADVANCED BASIC ENGINE
30 REM ========================================================================
=
40 CLS: SCREEN 176, 184: REM MATCH ORIGINAL VIC-20 CANVAS RESOLUTION
50 SETGRAVITY 0.0156: REM INJECTS CONSTANT DOWNWARD ACCELERATION INTO
ENVIRONMENT

60 REM --- INITIALIZE SCENERY & PADS ---
70 RANDOMTERRAIN 10, 150, 184: REM GENERATE BASELINE BETWEEN Y:150 AND Y:184
80 RECT 1, 20, 160, 40, 165, 2: REM PAD 1: X:20-40, Y:160-165, SCORE
MULTIPLIER 2X
90 RECT 2, 110, 155, 135, 160, 5: REM PAD 2: X:110-135, Y:155-160, SCORE
MULTIPLIER 5X

100 REM --- DECLARE SPRITES ---
110 SPRITE 1, "LANDER": REM ENGINE LOADS INTERNAL SHAPE AND SETS HANDLE TO ID
1
120 FUEL = 800: SAFEVEL = 1.15: REM SET PERFORMANCE PARAMS
130 PX = 80: PY = 10: REM SET START POSITIONS FOR TOP-CENTER SPOTS
140 MOVE SPRITE 1, PX, PY: REM SNAP TO START LOCATION

150 REM =======================================================================
==
160 REM                        MAIN GAME ENGINE LOOP
170 REM =======================================================================
==
180 K$ = INKEY$
190 IF FUEL <= 0 THEN GOTO 320: REM LOCK THRUSTERS OUT IF DRIED OUT

200 REM --- VERTICAL THRUST REGISTER UPDATES ---
210 IF K$ = "F1" THEN ADDSPEEDY 1, -0.0703: FUEL = FUEL - 3: GOTO 240: REM
HARD
220 IF K$ = "F3" THEN ADDSPEEDY 1, -0.0390: FUEL = FUEL - 2: GOTO 240: REM
MEDIUM
230 IF K$ = "F5" THEN ADDSPEEDY 1, -0.0234: FUEL = FUEL - 1: GOTO 240: REM
LIGHT

240 REM --- HORIZONTAL THRUST REGISTER UPDATES ---
250 IF K$ = "A" THEN ADDSPEEDX 1, -0.0312: FUEL = FUEL - 0.5: REM LEFT THRUST
260 IF K$ = "D" THEN ADDSPEEDX 1,  0.0312: FUEL = FUEL - 0.5: REM RIGHT THRUST

270 REM --- SYSTEM UPDATES ---
280 REM BACKGROUND ENGINE NOW AUTOMATICALLY ADDS GRAVITY TO SPEEDY, 
290 REM MULTIPLIES SPEED BY INERTIA, UPDATES PX/PY POSITION VALUES, AND BLITS
300 GOSUB 500: REM RUN LIVE HUD INTERFACE ROUTINE
310 WAIT VBLANK: REM STABILIZE SYSTEM INTERRUPT TIMING TO EXACTLY 60HZ

320 REM --- CONTINUOUS BACKGROUND PHYSICS INTERSECTION CHECKS ---
330 CHECKCOLLISION 1 INTO C: REM CHECK THE STATUS OF SPRITE 1 AGAINST
ENVIRONMENT
340 IF C = 0 THEN GOTO 180: REM SAFELY IN MID-AIR, CONTINUE LOOP

350 REM =======================================================================
==
360 REM                        TOUCHDOWN EVALUATION
370 REM =======================================================================
==
380 GETSPEEDY 1 INTO VY: REM POLL LIVE ACCUMULATED SPEED VAL FROM SPRITE
390 IF C = -1 THEN GOTO 460: REM HIT ROCKY GROUND (IMPACT FAILURE)

400 REM --- PAD LANDING LOGIC EVALUATION ---
410 IF VY > SAFEVEL THEN GOTO 460: REM CRASHED ON PAD (VELOCITY TOO HIGH)
420 PRINT "SUCCESSFUL TOUCHDOWN!"
430 POINTS = 100 * C: REM C CONTAINS TARGET MULTIPLIER INT (2 OR 5)
440 PRINT "SCORE AWARDED: "; POINTS
450 END

460 REM --- IMPACT FAILURE ROUTINE ---
470 SPRITE 1, "EXPLOSION": REM CHANGE ASSET MODEL MESH TO SMOKE/SHRAPNEL
EFFECT
480 PRINT "BOOM! LANDER DESTROYED."
490 END

500 REM =======================================================================
==
510 REM                            UI DISPLAY HUD
520 REM =======================================================================
==
530 LOCATE 1, 1: PRINT "FUEL: "; INT(FUEL); "  "
540 LOCATE 1, 20: GETSPEEDY 1 INTO VY
550 IF VY > SAFEVEL THEN COLOR 2: REM SET WARNING RED
560 IF VY <= SAFEVEL THEN COLOR 5: REM SET SAFE GREEN
570 LOCATE 1, 15: PRINT "SPEED: "; VY
580 COLOR 1: REM RESET FOREGROUND DISPLAY COLOR BALANCES
590 RETURN