00010 REM CLASSIC SOKOBAN MULTI-LEVEL ENGINE FOR MICROBEE
00020 CLEAR 2000:CLS:PRINT "--- CLASSIC SOKOBAN ---":PRINT
00030 DIM M$(20):REM MAX 20 ROWS PER MAP
00040 L=1:REM START AT LEVEL 1
00050 GOSUB 00500:REM LOAD SELECTED LEVEL L
00060 GOSUB 00600:REM RENDER MAP AND STATS
00070 REM MAIN GAME LOOP
00080 K$=INKEY$:IF K$="" THEN 00080
00090 DX=0:DY=0
00100 IF K$="W" OR K$="w" THEN DY=-1
00110 IF K$="S" OR K$="s" THEN DY=1
00120 IF K$="A" OR K$="a" THEN DX=-1
00130 IF K$="D" OR K$="d" THEN DX=1
00140 IF K$="R" OR K$="r" THEN GOTO 00050:REM RESTART LEVEL
00150 IF DX=0 AND DY=0 THEN 00080
00160 REM CHECK DESTINATION CELLS
00170 NX=PX+DX:NY=PY+DY:REM NEXT CELL
00180 NNX=PX+2*DX:NNY=PY+2*DY:REM CELL BEYOND
00190 IF NY<1 OR NY>H OR NX<1 OR NX>LEN(M$(NY)) THEN 00080
00200 C1$=MID$(M$(NY),NX,1)
00210 IF NNY>=1 AND NNY<=H AND NNX>=1 AND NNX<=LEN(M$(NNY)) THEN C2$=MID$(M$(NNY),NNX,1) ELSE C2$="#"
00220 IF C1$="#" THEN 00080:REM WALL COLLISION
00230 REM PUSHING A BOX
00240 IF C1$<>"$" AND C1$<>"*" THEN GOTO 00320
00250 IF C2$="#" OR C2$="$" OR C2$="*" THEN 00080
00260 REM MOVE BOX TO BEYOND CELL
00270 IF C2$="." THEN NC2$="*" ELSE NC2$="$"
00280 GOSUB 00800:REM UPDATE CELL NNX,NNY WITH NC2$
00290 IF C1$="*" THEN NC1$="." ELSE NC1$=" "
00300 GOSUB 00700:REM UPDATE CELL NX,NY WITH NC1$
00320 REM MOVE PLAYER TO NEXT CELL
00330 C1$=MID$(M$(NY),NX,1)
00340 IF C1$="." THEN NC1$="+" ELSE NC1$="@"
00350 GOSUB 00700:REM UPDATE CELL NX,NY WITH NC1$
00360 CP$=MID$(M$(PY),PX,1)
00370 IF CP$="+" THEN NCP$="." ELSE NCP$=" "
00380 GOSUB 00900:REM UPDATE CELL PX,PY WITH NCP$
00390 PX=NX:PY=NY:GOSUB 00600:REM REDRAW
00400 GOSUB 00440:IF W=1 THEN PRINT "LEVEL ";L;" CLEARED!":FOR T=1 TO 2000:NEXT T:L=L+1:GOTO 00050
00410 GOTO 00080
00440 REM WIN CONDITION CHECK
00450 W=1:FOR I=1 TO H:FOR J=1 TO LEN(M$(I))
00460 IF MID$(M$(I),J,1)="$" THEN W=0
00470 NEXT J:NEXT I:RETURN
00500 REM PARSE LEVEL FROM DATA STATEMENTS
00510 RESTORE:FOR I=1 TO L:READ H:FOR J=1 TO H:READ M$(J):NEXT J:NEXT I
00520 REM LOCATE PLAYER POSITION
00530 FOR I=1 TO H:FOR J=1 TO LEN(M$(I)):C$=MID$(M$(I),J,1)
00540 IF C$="@" OR C$="+" THEN PX=J:PY=I
00550 NEXT J:NEXT I:RETURN
00600 REM SCREEN RENDER
00610 CLS:PRINT "--- CLASSIC SOKOBAN - LEVEL ";L;" ---":PRINT
00620 FOR I=1 TO H:PRINT M$(I):NEXT I
00630 PRINT:PRINT "WASD = MOVE  |  R = RESTART LEVEL"
00640 RETURN
00700 REM HELPER: UPDATE NX,NY WITH NC1$
00710 M$(NY)=LEFT$(M$(NY),NX-1)+NC1$+MID$(M$(NY),NX+1):RETURN
00800 REM HELPER: UPDATE NNX,NNY WITH NC2$
00810 M$(NNY)=LEFT$(M$(NNY),NNX-1)+NC2$+MID$(M$(NNY),NNX+1):RETURN
00900 REM HELPER: UPDATE PX,PY WITH NCP$
00910 M$(PY)=LEFT$(M$(PY),PX-1)+NCP$+MID$(M$(PY),PX+1):RETURN
01000 REM --- LEVEL DATA PACK ---
01010 REM LEVEL 1 (CLASSIC #1)
01020 DATA 9
01030 DATA "  #####"
01040 DATA "  #   #"
01050 DATA "  #$  #"
01060 DATA "###  $##"
01070 DATA "#  $ $ #"
01080 DATA "### # ## #   ######"
01090 DATA "  # # ## #####  ..#"
01100 DATA "  # @ $          ..#"
01110 DATA "  ##### ### #@##  ..#"
01120 REM LEVEL 2 (CLASSIC #2)
01130 DATA 10
01140 DATA "############"
01150 DATA "#..  #     #"
01160 DATA "#..  # $   #"
01170 DATA "#..  #$ $  #"
01180 DATA "#..    $   #"
01190 DATA "#..  #     #"
01200 DATA "###### #####"
01210 DATA "  #  $ $ #"
01220 DATA "  # $ @  #"
01230 DATA "  ########"
01240 REM LEVEL 3 (CLASSIC #3)
01250 DATA 8
01260 DATA "  #######"
01270 DATA "  #     #"
01280 DATA "  # $ $ #"
01290 DATA "### $ $ ###"
01300 DATA "#   $@$   #"
01310 DATA "# ..   .. #"
01320 DATA "# .. $ .. #"
01330 DATA "###########"
01340 REM LEVEL 4 (CLASSIC #4 VARIANT)
01350 DATA 11
01360 DATA "  ####"
01370 DATA "###  ####"
01380 DATA "# $ $   #"
01390 DATA "#   #   #"
01400 DATA "# #@# $ #"
01410 DATA "# # .   #"
01420 DATA "#  ...###"
01430 DATA "####  #"
01440 DATA "   ####"
01450 DATA "   #  #"
01460 DATA "   ####"
01470 REM LEVEL 5 (THE TIGHT CORRIDORS)
01480 DATA 9
01490 DATA "#####"
01500 DATA "#@  ####"
01510 DATA "# $ $  #"
01520 DATA "#  # $ #"
01530 DATA "## #   #"
01540 DATA "#.. .. #"
01550 DATA "#..#   #"
01560 DATA "########"
01570 REM LEVEL 6 (THE SPLIT ROOM)
01580 DATA 10
01590 DATA "  ######"
01600 DATA "###    ###"
01610 DATA "#  $$#   #"
01620 DATA "# @  $   #"
01630 DATA "###  #####"
01640 DATA "  #  #"
01650 DATA "  #..#"
01660 DATA "  #..#"
01670 DATA "  #..#"
01680 DATA "  ####"