This file is part of and Timex Sinclair Public Domain Library Tape 1007. Download the collection to get this file.
You are faced with the task of exploring a sacred mountain of the Aztecs, in which one of their great leaders is rumoured to be buried along with untold riches in ancient relics. The only clue you have is that you must seek out a key which closely resembles a dollar sign.
Program Analysis
“Curse of the Aztec Tomb” is a text-graphics adventure/action game in which the player guides a character (“O”) down a pyramid-shaped mountain, dodging a rolling boulder, navigating a drawbridge, evading a lowering ceiling trap, collecting a dollar-sign key, and ultimately reaching the inner tomb treasure. The pyramid is drawn using a staircase of “% %” character pairs and block graphics characters to represent cliffs and terrain features. Player movement is controlled by keys “1” (move forward/left) and “0” (jump), with the game polling INKEY$ directly in a tight loop rather than using PAUSE-based input. The scoring system awards and deducts points for various actions, with a maximum bonus of 2,500 points for finding the treasure, and multiple death endings each deducting 500 points before restarting. Several random events (snake bite, falling ceiling, drawbridge collapse) are triggered using INT(RND*N) comparisons scattered through the game loop.
Program Structure
The program is organised into distinct functional blocks, separated by line-number ranges:
- Lines 45–90: Initialisation — jumps to the title/instructions at line 9500, then sets up all game variables.
- Lines 100–500: Main game loop — draws the boulder (“O”), moves it diagonally down-right each iteration, checks for collision with the target position, and polls for keypresses.
- Lines 2000–2020: Subroutine to reset the boulder’s starting position (row 3, column 13).
- Lines 3000–3018: “Move forward” handler — moves the player target left and up; triggers the next phase at line 3500 when
Y=2. - Lines 3200–3300: “Jump” handler — repositions the target and animates the boulder past a segment.
- Lines 3500–3740: Cliff-top/drawbridge phase — the player crosses a ledge, with further key-based movement and random events.
- Lines 4000–4140: Subroutine animating the player moving along the drawbridge approach.
- Lines 4200–4260: Moat drowning sequence — animates the “+” falling into water, leading to the moat death ending at 9350.
- Lines 4400–5100: Inner tomb section — random chance of a bat/creature appearing (flag
V), scored movement, and key polling. - Lines 5300–5380: Creature departure animation, restoring the
M(movement allowed) flag. - Lines 5500–5790: Cliff-dive sequence — player jumps and falls; detects landing on the creature (
V=1) vs. falling off the cliff. - Lines 6000–6110: Underground river/tunnel navigation with random drawbridge collapse event.
- Lines 6300–6330: Move right in tunnel.
- Lines 6700–6810: Drawbridge collapse animation.
- Lines 6850–6890: Drawbridge death ending.
- Lines 6900–6970: Jump up in tunnel.
- Lines 7200–7295: Lowering ceiling trap animation (flickering inverse characters).
- Lines 7350–7480: Ceiling death ending.
- Lines 7800–7999: Key/treasure room — snake encounter, treasure found ending, cobra death.
- Lines 9000–9200: Subroutine drawing the pyramid graphic using “% %” pairs and block-graphic characters.
- Lines 9300–9410: Boulder squash, moat, and other death endings.
- Lines 9500–9720: Title screen with inverse-video banner and instructions.
- Lines 9730–9750: Save block.
Main Game Loop
The core loop runs from approximately line 270 (referenced by GOTO 270 at line 500, though line 270 is absent — the interpreter falls through to line 280). Each iteration erases the boulder’s previous position with a space at AT A-1,C-1, resets the boulder to the top if it reaches row 21 (GOSUB 2000), draws it at AT A,C;"O", decrements the score by 25, then increments both A (row) and C (column) to move the boulder diagonally. A collision check at line 333 tests whether the boulder has caught the player marker “+” at position (Y,X).
Notable Techniques
- Absent target line as fall-through:
GOTO 270andGOTO 240target non-existent lines; the interpreter advances to the next higher-numbered line (280 and 280 respectively), which is a deliberate ZX BASIC technique to skip ahead cleanly. - Block graphic pyramid: The pyramid subroutine at 9000–9200 builds a staircase shape by printing progressively wider rows of
% %pairs (each%being a space character in context, producing a pattern), with\:block graphics (▌) used for the cliff face indentation at lines 9060–9080. - State flags:
Vtracks whether the creature is visible/present;Mcontrols whether the player can move;M1records whether the player has previously entered the inner tomb;Gflags that the drawbridge has collapsed. - Ceiling flicker animation: Lines 7200–7295 alternate between inverse
\~~and inverse\@@characters with a nullREM/RETURNsubroutine at 7300–7310 acting as a minimal delay loop. - Treasure flash loop: Lines 7970–7980 form an infinite loop alternating
**, inverse%*%*, and block graphic\@@\@@characters to animate a glittering treasure effect — the game never exits this loop normally. - Score as difficulty metric: The score is simultaneously a progress reward and a time penalty; the main loop deducts 25 points per iteration, encouraging the player to act quickly.
Key Variables
| Variable | Role |
|---|---|
A | Boulder row position |
C | Boulder column position |
X | Player target column |
Y | Player target row |
S | Score (starts at 1000) |
V | Creature present flag (0/1) |
M | Movement permitted flag (0/1) |
M1 | Inner tomb visited flag |
G | Drawbridge collapsed flag |
D | Snake strike counter (0–6) |
Bugs and Anomalies
- Typographical error: Line 9303 prints
"YPU HAVE BEEN SQUASHED"— “YPU” should be “YOU”. - Typographical error: Line 7400 prints
"UNSUSPECTING EXLOPLORERS"— “EXLOPLORERS” should be “EXPLORERS”. - Typographical error: Line 9305 prints
"YOUR CERTAINLY NOT"— “YOUR” should be “YOU’RE”. - Dead subroutine code: Line 7320 (
LET S=S-300) is unreachable — execution flows from theRETURNat 7310 back to the caller, so 7320 is never executed. - Line 9060 block graphics:
\:produces a half-block character (▌) used for the cliff indentation, giving an irregular left edge to the pyramid — this appears intentional for visual effect. - Potentially infinite jump-death sub-loop: Line 5678 deducts 750 points, prints a cliff-base graphic, then (if
G=0) CLSs and restarts from line 50, but ifG=1it goes to 6850 for the drawbridge death — this interaction is logically consistent. - Line 3595 out-of-range guard:
IF X>12 THEN LET X=12prevents the player marker from going off the right of the drawbridge section, but the earlier movement code at 3710 already decrements X, so this guard is a defensive check for edge cases.
Content
Image Gallery
Source Code
45 GOTO 9500
50 LET X=28
55 LET M=1
60 LET Y=18
65 LET G=0
70 LET S=1000
75 LET M1=0
80 LET V=0
90 GOSUB 9000
100 GOSUB 2000
280 PRINT AT A-1,C-1;" "
285 IF A=21 THEN GOSUB 2000
290 PRINT AT A,C;"O"
300 LET S=S-25
303 LET A=A+1
305 LET C=C+1
333 IF A=Y AND C=X THEN GOTO 9300
350 PRINT AT Y,X;"+"
360 IF INKEY$="1" THEN GOSUB 3000
370 IF INKEY$="0" THEN GOTO 3200
500 GOTO 270
\n2000 LET A=3
\n2010 LET C=13
\n2020 RETURN
\n3000 LET X=X-1
\n3005 LET S=S+100
\n3010 LET Y=Y-1
\n3015 PRINT AT Y+1,X+1;" "
\n3017 IF Y=2 THEN GOTO 3500
\n3018 RETURN
\n3200 PRINT AT Y,X;" "
\n3210 LET S=S-200
\n3220 LET Y=Y-2
\n3230 PRINT AT Y,X;"+"
\n3235 IF C=X-1 THEN GOTO 3240
\n3236 PRINT AT Y,X;" "
\n3237 LET Y=Y+2
\n3238 GOTO 240
\n3240 PRINT AT A-1,C-1;" "
\n3245 FOR Q=1 TO 3
\n3250 PRINT AT A,C;" "
\n3260 LET A=A+1
\n3270 LET C=C+1
\n3280 PRINT AT A,C;"O"
\n3290 NEXT Q
\n3295 PRINT AT A,C;" "
\n3300 GOTO 3236
\n3500 LET X=12
\n3510 LET Y=2
\n3520 LET S=S+300
\n3530 PRINT AT Y,X;"+"
\n3550 IF X=4 THEN GOTO 3560
\n3555 IF INKEY$="0" THEN GOSUB 4000
\n3560 IF INKEY$="1" THEN GOTO 3700
\n3570 IF X=10 AND Y=2 THEN GOTO 4200
\n3580 IF X=7 AND Y=2 THEN GOTO 4200
\n3585 LET S=S-25
\n3590 IF X=5 AND Y=2 THEN GOTO 4200
\n3595 IF X>12 THEN LET X=12
\n3600 IF X=3 THEN GOTO 4400
\n3620 GOTO 3530
\n3700 PRINT AT Y,X;" "
\n3710 LET X=X-1
\n3720 LET S=S+100
\n3730 PRINT AT Y,X;"+"
\n3735 IF X=9 THEN GOTO 3560
\n3740 GOTO 3570
\n4000 LET Y=Y-1
\n4010 PRINT AT Y+1,X;" "
\n4020 PRINT AT Y,X;"+"
\n4030 LET Y=Y-1
\n4040 LET X=X-1
\n4050 PRINT AT Y+1,X+1;" "
\n4060 PRINT AT Y,X;"+"
\n4070 LET Y=Y+1
\n4080 LET X=X-1
\n4090 PRINT AT Y-1,X+1;" "
\n4100 LET Y=Y+1
\n4110 PRINT AT Y-1,X;" "
\n4120 PRINT AT Y,X;"+"
\n4130 LET S=S-75
\n4140 GOTO 3570
\n4200 FOR Z=1 TO 9
\n4210 PRINT AT Y,X;" "
\n4220 LET Y=Y+1
\n4230 PRINT AT Y,X;"+"
\n4240 NEXT Z
\n4250 PRINT AT Y,X;"\@@"
\n4260 GOTO 9350
\n4400 LET S=S+300
\n4500 LET S=S-10
\n4507 IF INT (RND*10)=1 THEN GOTO 5000
\n4510 IF INT (RND*10)=2 THEN GOTO 5300
\n4520 IF INKEY$="0" THEN GOTO 5500
\n5000 IF V=1 THEN GOTO 4500
\n5010 LET V=1
\n5015 LET M=0
\n5020 PRINT AT 9,3;" ";AT 10,3;" ";AT 11,3;" "
\n5021 PRINT AT 9,1;"\ .";AT 10,1;"\'.";AT 11,2;"\'."
\n5024 PRINT AT 9,1;" ";AT 10,1;" ";AT 11,2;" "
\n5050 PRINT AT 9,0;"\ .";AT 10,1;"\'.";AT 11,2;"\'."
\n5075 PRINT AT 9,0;" ";AT 10,1;" ";AT 11,2;" "
\n5080 PRINT AT 10,0;"\ .";AT 11,1;"\''\.."
\n5085 PRINT AT 10,0;" ";AT 11,1;" "
\n5090 PRINT AT 12,0;"\''\''\''"
\n5100 GOTO 4500
\n5300 IF V=0 THEN GOTO 4500
\n5310 LET V=0
\n5315 LET M=1
\n5320 PRINT AT 12,0;" "
\n5325 PRINT AT 10,0;"\ .";AT 11,1;"\''\.."
\n5327 PRINT AT 10,0;" ";AT 11,1;" "
\n5330 PRINT AT 9,0;"\ .";AT 10,1;"\'.";AT 11,2;"\'."
\n5340 PRINT AT 9,0;" ";AT 10,1;" ";AT 11,2;" "
\n5350 PRINT AT 9,1;"\ .";AT 10,1;"\'.";AT 11,2;"\'."
\n5355 PRINT AT 9,1;" ";AT 10,1;" ";AT 11,2;" "
\n5360 PRINT AT 9,0;" ";AT 10,1;" ";AT 11,2;" "
\n5370 PRINT AT 9,3;"\: ";AT 10,3;"\: ";AT 11,3;"\: "
\n5375 IF M=1 AND M1=1 THEN GOTO 5540
\n5380 GOTO 4500
\n5500 LET M1=1
\n5505 PRINT AT Y,X;" "
\n5510 LET S=S+100
\n5520 LET Y=Y-1
\n5530 PRINT AT Y,X;"+"
\n5531 IF M=1 THEN GOTO 5540
\n5532 IF INT (RND*3)=1 THEN GOTO 8000
\n5540 LET Y=Y-1
\n5550 LET X=X-1
\n5560 PRINT AT Y+1,X+1;" "
\n5570 PRINT AT Y,X;"+"
\n5580 LET Y=Y+1
\n5590 LET X=X-1
\n5600 PRINT AT Y-1,X+1;" "
\n5610 PRINT AT Y,X;"+"
\n5620 FOR K=1 TO 10
\n5630 PRINT AT Y,X;" "
\n5640 LET Y=Y+1
\n5650 PRINT AT Y,X;"+"
\n5660 IF Y=11 AND V=1 THEN GOTO 6000
\n5670 NEXT K
\n5678 LET S=S-750
\n5680 PRINT AT 18,0;"\.:\. "
\n5685 PRINT AT 19,0;"\ :"
\n5690 FOR J=1 TO 50
\n5695 NEXT J
\n5696 IF G=1 THEN GOTO 6850
\n5697 CLS
\n5700 PRINT " GOOD GRIEF, WHO DO YOU THINK"
\n5710 PRINT "YOU ARE, SUPERMAN. FANCY DOING"
\n5720 PRINT "A SWAN DIVE OFF THE TOP OF A"
\n5730 PRINT "CLIFF. WHAT SOME PEOPLE WILL DO"
\n5740 PRINT "FOR A BIT OF AZTEC TREASURE."
\n5750 PRINT
\n5760 PRINT "YOU SCORED ";S
\n5770 PRINT "PRESS N/L TO RE-START"
\n5780 IF INKEY$="" THEN GOTO 5780
\n5785 CLS
\n5790 GOTO 50
\n6000 IF INT (RND*3)=2 THEN GOTO 6700
\n6030 LET S=S-15
\n6050 IF X>8 THEN LET X=8
\n6055 IF X=4 AND INT (RND*5)=2 THEN GOTO 7200
\n6057 IF X=8 THEN GOTO 7800
\n6060 IF INKEY$="1" THEN GOTO 6300
\n6070 IF INKEY$="0" THEN GOTO 6900
\n6110 GOTO 6050
\n6300 LET X=X+1
\n6310 PRINT AT Y,X-1;" "
\n6320 PRINT AT Y,X;"+"
\n6325 LET S=S+100
\n6330 GOTO 6050
\n6700 LET Y1=12
\n6710 LET X1=0
\n6720 PRINT AT Y1-1,X1;" "
\n6730 PRINT AT Y1,X1;"\'./\.'"
\n6740 LET Y1=Y1+1
\n6750 PRINT AT Y1,X1;"-/-";AT Y1,X1;"\' \ .>"
\n6760 IF Y1=19 THEN GOTO 6800
\n6770 PRINT AT Y1,X1;" "
\n6780 GOTO 6740
\n6800 LET G=1
\n6810 GOTO 5680
\n6850 CLS
\n6851 LET S=S-500
\n6853 PRINT " HARD LUCK. THE DRAWBRIDGE HAS"
\n6855 PRINT "COLLAPSED AND YOU HAVE FALLEN TO"
\n6860 PRINT "YOUR DEATH."
\n6865 PRINT
\n6870 PRINT "YOU SCORED ";S
\n6875 PRINT
\n6880 PRINT "PRESS N/L TO RE-START"
\n6885 IF INKEY$="" THEN GOTO 6885
\n6887 CLS
\n6890 GOTO 50
\n6900 LET Y=Y-2
\n6910 PRINT AT Y+2,X;" "
\n6920 PRINT AT Y,X;"+"
\n6930 IF X=9 THEN GOTO 7000
\n6940 LET Y=Y+2
\n6950 PRINT AT Y-2,X;" "
\n6960 PRINT AT Y,X;"+"
\n6970 GOTO 6050
\n7200 PRINT AT 9,3;"\~~\~~\~~"
\n7210 GOSUB 7300
\n7220 PRINT AT 9,3;"\@@\@@\@@"
\n7230 GOSUB 7300
\n7240 PRINT AT 10,3;"\~~\~~\~~"
\n7250 GOSUB 7300
\n7260 PRINT AT 10,3;"\@@\@@\@@"
\n7270 GOSUB 7300
\n7280 PRINT AT 11,3;"\~~\~~\~~"
\n7290 GOSUB 7300
\n7295 PRINT AT 11,3;"\@@\@@\@@"
\n7297 GOTO 7350
\n7300 REM
\n7310 RETURN
\n7320 LET S=S-300
\n7350 CLS
\n7360 PRINT " AN INTERESTING FEATURE OF "
\n7370 PRINT "AZTEC ARCHITECTURE IS THE CLEVER"
\n7380 PRINT "LITTLE CEILINGS THAT LOWER "
\n7390 PRINT "THEMSELVES DOWN ON TOP OF"
\n7400 PRINT "UNSUSPECTING EXLOPLORERS"
\n7410 PRINT "ESPECIALLY WHEN THEY ARE ONLY"
\n7420 PRINT "YARDS AWAY FROM THE FABULOUS"
\n7430 PRINT "TREASURES OF THE INNER TOMB."
\n7440 PRINT
\n7450 PRINT "YOU SCORED ";S
\n7455 PRINT
\n7460 PRINT "PRESS N/L TO RE-START"
\n7470 IF INKEY$="" THEN GOTO 7470
\n7475 CLS
\n7480 GOTO 50
\n7800 PRINT AT 9,8;"$"
\n7805 LET D=0
\n7810 IF D=6 THEN GOTO 7985
\n7815 IF INKEY$="0" THEN GOTO 7850
\n7820 GOTO 7810
\n7850 IF INT (RND*8)=4 THEN GOTO 7900
\n7855 LET D=D+1
\n7857 LET S=S-50
\n7860 LET Y=Y-1
\n7865 PRINT AT Y+1,X;" ";AT Y,X;"+"
\n7870 LET Y=Y+1
\n7875 PRINT AT Y-1,X;" ";AT Y,X;"+"
\n7880 GOTO 7810
\n7900 LET Y=Y-2
\n7910 PRINT AT Y+2,X;" ";AT Y,X;"+"
\n7920 LET Y=Y+2
\n7930 PRINT AT Y-2,X;" ";AT Y,X;"+$"
\n7935 PRINT AT 0,0;"CONGRATULATIONS, YOU HAVE FOUND"
\n7940 PRINT "THE AZTEC TREASURE AND SCORED "
\n7944 LET S=S+2500
\n7945 PRINT S
\n7950 PRINT AT 11,10;" "
\n7955 PRINT AT 9,11;" "
\n7960 PRINT AT 10,11;" "
\n7965 PRINT AT 11,11;" "
\n7970 PRINT AT 11,12;"**";AT 11,12;"%*%*";AT 11,12;"\@@\@@"
\n7975 PRINT AT 10,12;"**";AT 10,12;"%*%*";AT 10,12;"\@@\@@"
\n7980 GOTO 7970
\n7985 FOR J=1 TO 30
\n7986 NEXT J
\n7987 CLS
\n7990 PRINT " YOU HAVE BEEN BITTEN BY A"
\n7992 PRINT "DEADLY KING COBRA. NOT A LOT YOU"
\n7994 PRINT "CAN DO ABOUT THAT, YOU FORGOT TO"
\n7996 PRINT "BRING SOMEONE TO SUCK OUT THE"
\n7997 PRINT "POISON."
\n7998 LET S=S-250
\n7999 GOTO 9315
\n8000 LET M=1
\n8010 GOTO 5300
\n9000 PRINT AT 3,0;" % % % % % % % "
\n9010 PRINT " % % % % % % % % "
\n9020 PRINT " % % % % % % % % % "
\n9030 PRINT " % % % % % % % % % % % % % "
\n9040 PRINT " % % % % % % % % % % % % % % "
\n9050 PRINT " % % % % % % % % % % % % % % % "
\n9060 PRINT " \: \: % % % % % % % % % "
\n9070 PRINT " \: % % % % % % % % % % "
\n9080 PRINT " \: % % % % % % % % % % % "
\n9090 PRINT " % % % % % % % % % % % % % % % % % % % "
\n9100 PRINT " % % % % % % % % % % % % % % % % % % % % "
\n9110 PRINT " % % % % % % % % % % % % % % % % % % % % % "
\n9120 PRINT " % % % % % % % % % % % % % % % % % % % % % % "
\n9130 PRINT " % % % % % % % % % % % % % % % % % % % % % % % "
\n9140 PRINT " % % % % % % % % % % % % % % % % % % % % % % % % "
\n9150 PRINT " % % % % % % % % % % % % % % % % % % % % % % % % % "
\n9160 PRINT " % % % % % % % % % % % % % % % % % % % % % % % % % % "
\n9170 PRINT "% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % "
\n9180 PRINT "% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % "
\n9200 RETURN
\n9300 FOR J=1 TO 50
\n9301 NEXT J
\n9302 CLS
\n9303 PRINT " YPU HAVE BEEN SQUASHED BY A"
\n9305 PRINT "BOULDER. YOUR CERTAINLY NOT THE"
\n9310 PRINT "ATHLETIC TYPE ARE YOU ?"
\n9315 PRINT
\n9317 LET S=S-500
\n9320 PRINT "YOU SCORED ";S
\n9325 PRINT
\n9330 PRINT "PRESS N/L TO RE-START"
\n9335 IF INKEY$="" THEN GOTO 9335
\n9338 CLS
\n9340 GOTO 50
\n9350 FOR J=1 TO 50
\n9352 NEXT J
\n9353 LET S=S-500
\n9354 CLS
\n9355 PRINT " YOU HAVE DROWNED IN THE MOAT."
\n9360 PRINT "ISNT IT ABOUT TIME YOU LEARNT TO"
\n9365 PRINT "TO SWIM ? I SUPPOSE ITS A BIT "
\n9370 PRINT "LATE THOUGH NOW."
\n9375 PRINT
\n9380 PRINT "YOU SCORED ";S
\n9385 PRINT
\n9390 PRINT "PRESS N/L TO RE-START"
\n9395 IF INKEY$="" THEN GOTO 9395
\n9400 CLS
\n9410 GOTO 50
\n9500 PRINT AT 2,4;"%C%U%R%S%E% %O%F% %T%H%E% %A%Z%T%E%C% %T%O%M%B"
\n9510 PRINT AT 6,0;" YOU ARE FACED WITH THE TASK"
\n9520 PRINT "OF EXPLORING A SACRED MOUNTAIN"
\n9530 PRINT "OF THE AZTECS, IN WHICH ONE OF"
\n9540 PRINT "THEIR GREAT LEADERS IS RUMOURED"
\n9550 PRINT "TO BE BURIED ALONG WITH UNTOLD"
\n9560 PRINT "RICHES IN ANCIENT RELICS."
\n9570 PRINT " THE ONLY CLUE YOU HAVE IS "
\n9580 PRINT "THAT YOU MUST SEEK OUT A KEY "
\n9590 PRINT "WHICH CLOSELY RESEMBLES A DOLLAR"
\n9600 PRINT "SIGN."
\n9610 PRINT "BEWARE OF THE CURSE. THERE ARE"
\n9620 PRINT "MANY DANGERS TO FACE ON YOUR WAY"
\n9630 PRINT "TO THE TREASURE. GOOD LUCK."
\n9640 PRINT " KEY 1 ALLOWS YOU TO MOVE"
\n9650 PRINT "FORWARD AND KEY 0 ALLOWS YOU TO"
\n9660 PRINT "JUMP. PRESS N/L TO START"
\n9670 PRINT AT 0,0;"%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*"
\n9680 PRINT AT 4,0;"%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*%*"
\n9690 PRINT AT 1,0;"%*";AT 2,0;"%*";AT 3,0;"%*"
\n9700 PRINT AT 1,31;"%*";AT 2,31;"%*";AT 3,31;"%*"
\n9710 IF INKEY$="" THEN GOTO 9710
\n9715 CLS
\n9720 GOTO 50
\n9730 CLEAR
\n9740 SAVE "1032%0"
\n9750 RUN Note: Type-in program listings on this website use ZMAKEBAS notation for graphics characters.