10 REM CITADEL RANDOMISER 0.5
   20 REM by 'Diminished', March 2026
   30 REM this BASIC file will load from &1900 to about &5F80 ish,
   40 REM so we'll begin placing code and data from &6000 up.
   50 REM CITAX will load from &1900 to &5F00
   60 :
   70 MODE 7:CLEAR
   80 REM select assembly mode (0 or 1):
   90 LST%=0
  100 LST%=LST%+2
  110 AS%=FALSE:SD%=-1:DP%=FALSE
  120 REM page &A (the "stash page") hides away as CITAX is loaded; then it is moved to &7800
  130 REM all code and data for patching must reside in the stash page
  140 REM starts with room ID by item ID master table
  150 STASH%=&A00:HISTASH%=&7800:DTA%=STASH%+2:HIDTA%=HISTASH%+2:ISROFF%=&30:PAYLOADOFF%=&90:SEEDASCOFF%=&F0:OLDISROFF%=&FE
  160 :
  170 DIM ROOMS% 37:DIM SLV% 1:DIM PTS% 1:DIM AT% 1:DIM MAXAT% 1:DIM MINPTS% 1:DIM MINAT% 1:DIM IW% 1:DIM PRNGVARS% 12
  180 INV%=HISTASH%-&800: REM 40 items; give it half a page
  190 INSTALLER%=HISTASH%-&880: REM place ISR installer after it
  200 IBR%=HISTASH%-&700: REM goes up to e.g. IBR%+&EA so really needs a page
  210 REM code addresses start here:
  220 SHUF%=HISTASH%-&600: REM shuffle routine; one page
  230 PRNG%=HISTASH%-&500: REM RNG routine; two pages
  240 SOLVE%=HISTASH%-&300: REM solver routine; three pages
  250 PRINT "Assembling ..."'
  260 PROCasmMarsaglia
  270 PROCinitRooms
  280 PROCasmShufStuff
  290 PROCasmSolve
  300 CLS:PRINT "Citadel Randomiser v0.5":PRINT "(c) 'Diminished', March 2026"'
  310 PROCinst
  320 DA%=TRUE:REM DA%=FNyn("Disable attract mode spoilers"):REM v0.5: removed
  330 SLOW%=FNyn("Original (slower) game speed")
  340 DP%=FNyn("Show score for chosen seed")
  350 REM v0.5: fixed ambiguous question: stardot.org.uk/forums/viewtopic.php?p=239756#p239756
  360 ?IW%=NOT FNyn("Omit seeds needing trampo-warp")
  370 AS%=FNyn("Automatic randomisation seed"):IF AS% THEN 440
  380 REPEAT:INPUT "Enter seed: " SEED%:IF SEED%<=0 PRINT "Seed must be a positive integer."
  390 UNTIL SEED%>0
  400 ?MINAT%=0:?MINPTS%=0:!PRNGX%=SEED%:CALL SHUF%
  410 CALL SOLVE%:PROCprintScore:IF 1=?SLV% GOTO 560
  420 PRINT:PRINT CHR$(129);"Warning: This seed looks unsolvable!"'
  430 IF NOT FNyn("Are you sure") THEN PRINT "Aborting.":END ELSE 560
  440 P99%=FNyn("Only seeds giving 99 points")
  450 PL99%=FALSE:IF NOT P99% THEN PL99%=FNyn("Only seeds giving < 99 points")
  460 GI%=RND(-TIME)
  470 PRINT '"Looking for a suitable seed ..."'';:REPEAT
  480 SEED%=RND(999999999)
  490 ?MINAT%=0:?MINPTS%=0
  500 !PRNGX%=SEED%:CALL SHUF%
  510 CALL SOLVE%
  520 IF P99% AND ?PTS%<99 ?SLV%=0
  530 IF PL99% AND ?PTS%=99 ?SLV%=0
  540 PROCprintScore
  550 UNTIL ?SLV%=1:REM 2, 3, 0 are all errors
  560 PRINT:TP%=FNtape("Tape or disc version")
  570 PRINT:IF NOT FNyn("Ready. Load game") PRINT "Aborting.":END
  580 CLS:PROCbuildseedtext(SEED%):PROCsave(FNfindSarco, DA%, NOT SLOW%)
  590 IF NOT TP% THEN GOTO 620
  600 *TAPE
  610 PAGE=&E00
  620 CHAIN "CITADEL"
  630 END
  640 REM v0.5: build title screen ASCII for seed
  650 DEF PROCbuildseedtext(SD%)
  660 LOCAL DIGIT%,I%,J%,K%
  670 K%=STASH%+SEEDASCOFF%
  680 FOR I%=0 TO 13:?(K%+I%)=&20:NEXT
  690 FOR I%=3 TO 11:J%=(K%+I%):IF SD%=0 THEN ?J%=&20 ELSE DIGIT%=SD% MOD 10:SD%=SD% DIV 10:?J%=&30+DIGIT%
  700 NEXT:ENDPROC
  710 :
  720 DEF FNyn(M$)
  730 PRINT M$;" (Y/N)? ";
  740 LOCAL A$
  750 *FX15,1
  760 REPEAT:A$=GET$:UNTIL A$="y" OR A$="n" OR A$="Y" OR A$="N"
  770 PRINT A$
  780 =(A$="Y" OR A$="y")
  790 :
  800 DEF FNtape(M$)
  810 PRINT M$;" (T/D)? ";
  820 LOCAL A$
  830 *FX15,1
  840 REPEAT:A$=GET$:UNTIL A$="t" OR A$="d" OR A$="T" OR A$="D"
  850 PRINT A$
  860 =(A$="T" OR A$="t")
  870 :
  880 DEF PROCprintScore
  890 LOCAL XI%:XI%=0:IF ?SLV%>1 THEN XI%=?SLV%:?SLV%=0
  900 IF 1=?SLV% THEN 930
  910 IF AS% PRINT SEED%,; ELSE IF DP% PRINT 'CHR$133;SEED%,; ELSE PRINT 'CHR$133;SEED%';:ENDPROC
  920 GOTO 950
  930 IF AS% PRINT '"Found seed:"''CHR$133;SEED%; ELSE PRINT 'CHR$133;SEED%;
  940 IF NOT DP% THEN PRINT:ENDPROC
  950 IF XI%=2 PRINT ;CHR$135"(Ice crystal in sarcophagus)":ENDPROC
  960 IF XI%=3 PRINT ;CHR$135"(Chicken in sarcophagus)":ENDPROC
  970 IF ?MINAT%<>0 PRINT ;CHR$135"(rounds ";?MINAT%;"/";?MAXAT%;", points ";?MINPTS%;"/";?PTS%;")":ENDPROC
  980 PRINT ;CHR$135"(rounds ";?MAXAT%;", points ";?PTS%;")"
  990 ENDPROC
 1000 :
 1010 REM read the rooms-by-item-slot list into ROOMS%
 1020 DEF PROCinitRooms
 1030 LOCAL LI%,LJ%:RESTORE:FOR LI%=0 TO 36:READ LJ%:?(ROOMS%+LI%)=LJ%:NEXT
 1040 ENDPROC
 1050 :
 1060 DEF PROCasmShufStuff
 1070 PRINT "Shuffler"
 1080 REM this copies the initial room table into DTA% before the shuffle is done
 1090 FOR C=0 TO LST% STEP LST%
 1100 P%=SHUF%
 1110 [
 1120 OPT C
 1130 LDX #36
 1140 .L1
 1150 LDA ROOMS%,X
 1160 STA DTA%,X
 1170 DEX
 1180 BPL L1
 1190 LDA #&3F:PHA  \ mask
 1200 LDX #36
 1210 .LA0
 1220 JSR PRNG%
 1230 PLA:PHA   \ mask
 1240 AND PRNGX%+2   \ get one byte from the PRNG
 1250 STA PRNGV%
 1260 TXA
 1270 CMP PRNGV%
 1280 BCS LA1   \ repeat until we get a random number that's <= loop index
 1290 BNE LA0   \ ???
 1300 .LA1
 1310 LDA DTA%,X   \ get DTA% + LI%
 1320 PHA   \ push A (DTA% + LI%)
 1330 TXA:PHA   \ push X (loop counter)
 1340 LDX PRNGV%
 1350 LDA DTA%,X   \ get DTA% + LJ%
 1360 TAY:PLA:TAX   \ pop X
 1370 TYA:STA DTA%,X   \ *(DTA% + LI%) = *(DTA% + LJ%)
 1380 PLA:TAY:TXA:PHA:TYA:LDX PRNGV%:STA DTA%,X   \ *(DTA% + LJ%) = old *(DTA% + LI%)
 1390 PLA:TAX    \ loop counter
 1400 CMP #32:BNE LA2:PLA:LDA #&1F:PHA
 1410 .LA2:TXA:CMP #16:BNE LA3:PLA:LDA #&F:PHA
 1420 .LA3:TXA:CMP #8:BNE LA4:PLA:LDA #&7:PHA
 1430 .LA4:TXA:CMP #4:BNE LA5:PLA:LDA #&3:PHA
 1440 .LA5:DEX
 1450 BNE LA0
 1460 PLA
 1470 LDX #38   \ make space for the two missing elements (0x17, 0x30) and insert them
 1480 .L5
 1490 LDA DTA%-2,X   \ this is why we place DTA at A02 and not A00 ...
 1500 STA DTA%,X
 1510 DEX
 1520 CPX #29   \ so last iteration is 30
 1530 BNE L5
 1540 LDX #27:LDA DTA%,X:STA DTA%+1,X:LDA #&17:STA DTA%,X:LDA #&E1:STA DTA%+2,X   \ insert missing elements
 1550 LDX #0   \ zero out IBR table
 1560 LDA #0
 1570 .LZ
 1580 STA IBR%,X
 1590 INX
 1600 BNE LZ
 1610 LDX #38   \ this one builds the reverse lookup table, IBR%, after the shuffle is done
 1620 .L2
 1630 TXA:PHA
 1640 LDA DTA%,X
 1650 TAX
 1660 PLA
 1670 STA IBR%,X
 1680 TAX
 1690 DEX
 1700 BPL L2
 1710 RTS
 1720 ]
 1730 NEXT
 1740 PRINT"Shuffler ";(P%-SHUF%);" bytes"'
 1750 ENDPROC
 1760 :
 1770 DEF FNfindSarco
 1780 LOCAL LI%, LJ%
 1790 LJ%=&FF
 1800 FOR LI%=0 TO 38:IF ?(DTA%+LI%)=&3D LJ%=LI%
 1810 NEXT
 1820 IF LJ%=&2 THEN ?SLV%=0
 1830 IF LJ%=&FF PRINT "Error: Fixup failed.":END
 1840 =LJ%
 1850 :
 1860 DEF PROCsave(SI%,DA%,FAST%)
 1870 IF DA% THEN AMOP%=&E8 ELSE AMOP%=&C8
 1880 IF FAST% THEN FAST%=3 ELSE FAST%=4
 1890 REM A00 (7800) room data table (STASH%, HISTASH%)
 1900 REM A30 (7830) IRQ handler     (+ISROFF%)
 1910 REM A90 (7890) payload         (+PAYLOADOFF%)
 1920 REM ACE-ACF (78CE-78CF) saved old IRQ vector target (+OLDISROFF%)
 1930 :
 1940 PRINT "Building stash page ..."'
 1950 REM here is the ISR; it waits for memory to be modified, signalling that CITAX has finished loading
 1960 PRINT "ISR"
 1970 FOR C=0 TO LST% STEP LST%
 1980 P%=STASH%+ISROFF%
 1990 [
 2000 OPT C
 2010 PHA
 2020 TXA:PHA
 2030 TYA:PHA
 2040 LDA &5700   \ CITAX version
 2050 CMP #&B0
 2060 BEQ L1
 2070 PLA:TAY    \ memory not modified yet, return, pass control to OS
 2080 PLA:TAX
 2090 PLA
 2100 JMP (STASH%+OLDISROFF%) \ resume old saved vector target
 2110 .L1   \ initial check passed; check to see if relocation has happened yet
 2120 LDA &205
 2130 CMP #&78
 2140 BEQ LB
 2150 LDX #0   \ no? copy page &A00 (STASH%) to &7800 (HISTASH%)
 2160 .L2
 2170 LDA STASH%,X
 2180 STA HISTASH%,X
 2190 INX
 2200 CPX #0 \ stash page length (&100)
 2210 BNE L2
 2220 LDA #(ISROFF%)    \ risky... switch ISR vector from STASH to HISTASH
 2230 STA &204
 2240 LDA #(HISTASH% DIV 256)
 2250 STA &205
 2260 .LB:LDA &8A5 \&4C8  \ second check -- code being moved into position
 2270 CMP #&D6 \#&3C
 2280 BNE LX   \ no? return
 2290 LDA &4284   \ third check
 2300 CMP #&C8
 2310 BNE LX   \ no? return
 2320 LDA HISTASH%+OLDISROFF%    \ restore original OS handler
 2330 STA &204
 2340 LDA HISTASH%+OLDISROFF%+1
 2350 STA &205
 2360 JSR HISTASH%+PAYLOADOFF%   \ release the hounds
 2370 .LX:PLA:TAY   \ pass control to OS
 2380 PLA:TAX
 2390 PLA
 2400 .L35
 2410 JMP (HISTASH%+OLDISROFF%)  \ caution; indirect jump!
 2420 ]
 2430 NEXT
 2440 PRINT "ISR ";(P%-(STASH%+ISROFF%));" bytes"'
 2450 REM assemble the installer for ISR at A30, then execute installer
 2460 PRINT "Installer"
 2470 P%=INSTALLER%
 2480 [
 2490 OPT LST%
 2500 SEI
 2510 LDA &204
 2520 STA STASH%+OLDISROFF%
 2530 LDA &205
 2540 STA STASH%+OLDISROFF%+1
 2550 LDA #(ISROFF%)
 2560 STA &204
 2570 LDA #(STASH% DIV 256)
 2580 STA &205
 2590 CLI
 2600 RTS
 2610 ]
 2620 PRINT "Installer ";(P%-INSTALLER%);" bytes"'
 2630 REM assemble payload at &A90 (STASH%+PAYLOADOFF%)
 2640 REM "tile table address", "room table address"
 2650 REM point to the item we're going to change into the crystal
 2660 REM SI% may point off the end of the table, e.g. when unshuffled
 2670 REM in this case just hack it so the writes go to ROM instead
 2680 REM &590 was once &4C8, but it wouldn't patch reliably
 2690 REM now it's modified before game moves table down to 4C8
 2700 TTA%=SI%+&590:RTA%=SI%+&880:IF SI%=&26 THEN TTA%=&9000:RTA%=&9000
 2710 PRINT "Payload"
 2720 FOR C=0 TO LST% STEP LST%
 2730 P%=STASH%+PAYLOADOFF%
 2740 [
 2750 OPT C
 2760 \ copy room table to its destination
 2770 LDX #&25
 2780 .L3
 2790 LDA HIDTA%,X
 2800 STA &880,X
 2810 DEX
 2820 BPL L3
 2830 \ table copy done; TTA% is the item slot assigned to the &3D room (the pyramid sarco room)
 2840 \ there's no item pad in here, so it needs a patch -- look up the tile ID for this
 2850 \ item slot
 2860 LDA TTA%
 2870 \ and patch the sarcophagus routine with its tile ID
 2880 STA &2D89
 2890 \ now, we're going to use this item slot for something else -- the crystal
 2900 \ the crystal's tile ID is 2
 2910 LDA #&02
 2920 \ overwrite the 3D item's tile ID, so this item is now the crystal
 2930 STA TTA%
 2940 \ we also need to patch the new crystal item's room ID to the room that we want the crystal
 2950 \ to appear in, and this is in the final, "extra" entry in the room table (&26)
 2960 LDA HIDTA%+&26
 2970 STA RTA%
 2980 \ now, fix up the attract mode (or not) -- changes branch at &4283 (once relocated)
 2990 .L0:LDA #AMOP%
 3000 STA &4284
 3010 \ v0.5; patch title screen text
 3020 LDX #13
 3030 .P42
 3040 LDA HISTASH%+SEEDASCOFF%,X
 3050 STA &7DC,X
 3060 LDA #32 \ just delete drop-shadowed copy
 3070 STA &7C6,X
 3080 DEX
 3090 BNE P42
 3100 \ v0.5; patch game speed
 3110 LDA #FAST%
 3120 STA &4114
 3130 RTS
 3140 ]
 3150 NEXT
 3160 PRINT "Payload ";(P%-(STASH%+PAYLOADOFF%));" bytes"'
 3170 REM enable our ISR
 3180 TIME=0:REPEAT UNTIL TIME>60
 3190 CALL INSTALLER%
 3200 *FX 14,4
 3210 ENDPROC
 3220 :
 3230 DATA &72,&D5,&97,&6E,&01,&5E,&1C,&6F,&0B,&A6,&C4,&84,&68,&81,&36,&6C
 3240 DATA &87,&95,&05,&86,&85,&5C,&64,&82,&CB,&E4,&EA,&70,&58,&83
 3250 DATA &A3,&29,&5A,&90,&94,&D6
 3260 DATA &3D: REM this one is the added one, sarco room -- it's fixed up specially after the solver
 3270 :
 3280 DEF PROCasmSolve
 3290 PRINT "Solver"
 3300 REM attempt limit
 3310 ATLIMIT%=6
 3320 FOR C=0 TO LST% STEP LST%
 3330 P%=SOLVE%
 3340 [
 3350 OPT C
 3360 LDX #38
 3370 LDA #0
 3380 .P6   \ init inventory loop
 3390 STA INV%,X
 3400 DEX
 3410 BPL P6
 3420 LDA #1   \ collect initial twelve items
 3430 LDA IBR%+&5E:TAX:INC INV%,X
 3440 LDA IBR%+&84:TAX:INC INV%,X
 3450 LDA IBR%+&81:TAX:INC INV%,X
 3460 LDA IBR%+&6C:TAX:INC INV%,X
 3470 LDA IBR%+&87:TAX:INC INV%,X
 3480 LDA IBR%+&85:TAX:INC INV%,X
 3490 LDA IBR%+&5C:TAX:INC INV%,X
 3500 LDA IBR%+&82:TAX:INC INV%,X
 3510 LDA IBR%+&70:TAX:INC INV%,X
 3520 LDA IBR%+&58:TAX:INC INV%,X
 3530 LDA IBR%+&83:TAX:INC INV%,X
 3540 LDA IBR%+&5A:TAX:INC INV%,X
 3550 LDA #0:STA SLV%:STA AT%   \ attempts=0, solved=false
 3560 .P7      \ begin attempts loop
 3570 LDY #4:TYA:STA PTS%   \ start with 4 points
 3580 INC AT%:LDA AT%:STA MAXAT%   \ attempts++, max_attempts = attempts
 3590 LDA INV%+35:BEQ L8:INY:INY   \ handle points for crowns
 3600 .L8:LDA INV%+36:BEQ L9:INY:INY
 3610 .L9:LDA INV%+37:BEQ L10:INY:INY
 3620 .L10:LDA INV%+17:BEQ L11   \ no prison key
 3630 INY:INY   \ unlock prison => 2 points
 3640 LDA IBR%+&86:TAX:INC INV%,X   \ get prison item
 3650 LDA INV%+24:ORA INV%+30:BEQ L11:INY:INY:LDA IBR%+&72:TAX:INC INV%,X   \ if have either trampo then collect top item, red flask
 3660 .L11:LDA INV%+14:BEQ L15:INY:INY:INY   \ unlock well => 3 points (2 for door, 1 for flask)
 3670 LDA IBR%+&D5:TAX:INC INV%,X:LDA INV%+2:BEQ L12:LDA IBR%+&D6:TAX:INC INV%,X   \ get item at bottom of well, if ice crystal => crown pad item
 3680 .L12:LDA INV%+26:BEQ L13:LDA INV%+21:BEQ L13:INY:INY:LDA IBR%+&C4:TAX:INC INV%,X     \ both gunpowder & cannonball => lab item, red flask
 3690 .L13:LDA INV%+26:BEQ L14:INY:INY:INY   \ cannonball worth 3 points
 3700 .L14:LDA INV%+21:BEQ L15:INY:INY:INY   \ gunpowder worth 3 points
 3710 .L15   \ end of well
 3720 LDA INV%+11:BNE L16:JMP L22    \ wasteland unlock *** BRANCH POSSIBLY OUT OF RANGE?
 3730 .L16:INY:INY:INY               \ 2 points for door, 1 for flask; 4 items also available:
 3740 LDA IBR%+&EA:TAX:INC INV%,X    \ Mountains pad
 3750 LDA IBR%+&68:TAX:INC INV%,X    \ outside Witch's House
 3760 LDA IBR%+&64:TAX:INC INV%,X    \ desert
 3770 LDA IBR%+&1:TAX:INC INV%,X     \ pyramid pad 1
 3780 LDA INV%+0:ORA INV%+1:BEQ L17:LDA IBR%+&29:TAX:INC INV%,X:INY    \ either mask => pyramid pad 2, flask
 3790 .L17:LDA INV%+0:BEQ L18:LDA INV%+1:BEQ L18:LDA INV%+25:BEQ L18   \ both masks & statuette ...
 3800 INY:INY:INY:LDA IBR%+&3D:TAX:INC INV%,X   \ ... gets you the item in the sarcophagus, and 3 points
 3810 
 3820 .L18:LDA INV%+23:ORA INV%+24:ORA INV%+30:BEQ L22   \ no trampos, no barrel => skip witch
 3830 LDA IBR%+&90:TAX:INC INV%,X           \ witch crown pad item
 3840 LDA INV%+4:BEQ L19:INY:INY:INY        \ blue bone in cauldron gives 3 points
 3850 .L19:LDA INV%+5:BEQ L20:INY:INY:INY   \ magenta bone in cauldron gives 3 points
 3860 .L20:LDA INV%+6:BEQ L21:INY:INY:INY   \ skull in cauldron gives 3 points
 3870 .L21:LDA INV%+4:BEQ L22:LDA INV%+5:BEQ L22:LDA INV%+6:BEQ L22    \ all three cauldron items gets you ...
 3880 LDA IBR%+&A6:TAX:INC INV%,X:INY:INY:INY:INY:INY  \ ... lower item; 3 points for witch, 2 points for red flask
 3890 .L22   \ end of witch, end of wasteland
 3900 LDA INV%+16:BEQ L23:INY:INY:INY   \ unlock cellar, 2 pts for door, 1 for flask
 3910 LDA IBR%+&95:TAX:INC INV%,X:LDA IBR%+&97:TAX:INC INV%,X       \ 2 items
 3920 LDA INV%+24:ORA INV%+30:ORA INV%+23:BEQ L23:LDA IBR%+&94:TAX:INC INV%,X   \ if have either trampo (v0.5; or barrel), get crown item
 3930 .L23:LDA INV%+13:BEQ L24:INY:INY:INY:INY   \ unlock east tower; 2 pts for door, 2 for red flask
 3940 LDA INV%+2:BEQ L24:LDA IBR%+&36:TAX:INC INV%,X   \ ice crystal gets item
 3950 .L24:LDA INV%+12:BEQ L25:INY:INY:INY:INY   \ unlock west tower; 2 pts for door, 2 for red flask
 3960 LDA IBR%+&1C:TAX:INC INV%,X                \ item available
 3970 .L25:LDA INV%+15:BEQ L26:INY:INY:INY   \ unlock freezer; 2 pts for door, 1 for flask
 3980 LDA IBR%+&6E:TAX:INC INV%,X:LDA IBR%+&6F:TAX:INC INV%,X   \ two items available
 3990 .L26:LDA INV%+20:BEQ L27:INY:INY:LDA IBR%+&B:TAX:INC INV%,X:BNE L28   \ bucket; red flask + central tower item
 4000 .L27:LDA IW%:BEQ L28:LDA INV%+3:BEQ L28:LDA INV%+24:ORA INV%+30:BEQ L28   \ OR, island warp; chicken & one trampo ...
 4010 INY:INY:LDA IBR%+&B:TAX:INC INV%,X   \ also gets you a red flask and the central tower item
 4020 .L28:LDA INV%+3:BEQ L29:TYA:CLC:ADC #7:TAY   \ cook chicken; 3 pts, feed guardians; 3 pts, starport flask; 1 pt
 4030 LDA IBR%+&A3:TAX:INC INV%,X   \ item; star port
 4040 LDA IBR%+&CB:TAX:INC INV%,X   \ item; temple
 4050 LDA IBR%+&E4:TAX:INC INV%,X   \ item; ocean
 4060 .L29:LDA INV%+7:BEQ L30:INY:INY:INY:INY:INY   \ crystals give 5 pts each
 4070 .L30:LDA INV%+8:BEQ L31:INY:INY:INY:INY:INY
 4080 .L31:LDA INV%+9:BEQ L32:INY:INY:INY:INY:INY
 4090 .L32:LDA INV%+10:BEQ L33:INY:INY:INY:INY:INY
 4100 .L33:LDA INV%+38:BEQ L34:INY:INY:INY:INY:INY
 4110 .L34:LDA INV%+7:BEQ L37:LDA INV%+8:BEQ L37:LDA INV%+9:BEQ L37:LDA INV%+10:BEQ L37:LDA INV%+38:BEQ L37:LDA INV%+3:BEQ L37   \ 5 crystals + chicken
 4120 LDA IBR%+&5:TAX:INC INV%,X   \ use teleporter => get alien star port item
 4130 LDA INV%+18:BEQ L37:INY:INY:INY:INY:INY   \ unlock marduk door; 2 points + 3 points for star port destruction
 4140 LDA SLV%:BNE L36   \ solved, but have we solved it before?
 4150 .L39:TYA:STA MINPTS%:INC SLV%:LDA AT%:STA MINAT%:BNE L37   \ no! newly solved, so record min pts, min attempts needed
 4160 .L36:TYA:CMP #99:BNE L37:STA PTS%:BEQ L38  \ solved already ... if have 99 points, store points and quit
 4170 .L37   \ either solved previously @ <99 pts, not solved, or just solved => carry on
 4180 TYA:STA PTS%   \ store points
 4190 LDA AT%
 4200 CMP #ATLIMIT%
 4210 BEQ L38      \ enough attempts already, quit
 4220 JMP P7       \ next attempt
 4230 .L38         \ done
 4240 LDA DTA%+2   \ prevent ice crystal (IID 2) in sarcophagus bug
 4250 CMP #&3D     \ sarco chamber
 4260 BNE L40
 4270 LDA #2
 4280 STA SLV%     \ ice crystal in sarco => mark seed bad
 4290 \ v0.5; ban sarco chicken too; stardot.org.uk/forums/viewtopic.php?p=478777#p478777
 4300 .L40
 4310 LDA DTA%+3   \ chicken (IID 3)
 4320 CMP #&3D     \ sarco chamber
 4330 BNE L41
 4340 LDA #3
 4350 STA SLV%     \ chicken in sarco => seed bad
 4360 \ end v0.5
 4370 .L41:RTS
 4380 ]
 4390 NEXT
 4400 PRINT"Solver ";(P%-SOLVE%);" bytes"':TIME=0:REPEAT UNTIL TIME>50
 4410 ENDPROC
 4420 :
 4430 DEF PROCinst
 4440 PRINT CHR$131;"This software will load Citadel with"
 4450 PRINT CHR$131;"its item locations randomised."'
 4460 PRINT CHR$131;"Each supported permutation is"
 4470 PRINT CHR$131;"represented by a single integer or"
 4480 PRINT CHR$131;"'seed' in the range 1 to 999,999,999."
 4490 PRINT CHR$131;"The randomiser can either generate a"
 4500 PRINT CHR$131;"solvable seed automatically, or the"
 4510 PRINT CHR$131;"user may supply one."'
 4520 PRINT CHR$131;"The figurine on the alien planet"
 4530 PRINT CHR$131;"needed to complete the game remains"
 4540 PRINT CHR$131;"unrandomised in its original location."'
 4550 PRINT CHR$131;"Any item may appear in the three"
 4560 PRINT CHR$131;"secret rooms that normally contain"
 4570 PRINT CHR$131;"the crowns."'
 4580 ENDPROC
 4590 :
 4600 DEF PROCasmMarsaglia:REM needs a couple of pages
 4610 PRINT "RNG"
 4620 PRNGX%=PRNGVARS%:PRNGO%=PRNGVARS%+4:PRNGV%=PRNGVARS%+8
 4630 FOR C=0 TO LST% STEP LST%
 4640 P%=PRNG%
 4650 [
 4660 OPT C
 4670 PHA
 4680 TXA:PHA
 4690 TYA:PHA
 4700 \ shift left 13
 4710 LDA #0:STA PRNGO%
 4720 LDA PRNGX%:ASL A:ASL A:ASL A:ASL A:ASL A:STA PRNGO%+1
 4730 LDA PRNGX%:ROR A:ROR A:ROR A:AND #&1F:STA PRNGO%+2
 4740 LDA PRNGX%+1:ASL A:ASL A:ASL A:ASL A:ASL A:ORA PRNGO%+2:STA PRNGO%+2
 4750 LDA PRNGX%+1:ROR A:ROR A:ROR A:AND #&1F:STA PRNGO%+3
 4760 LDA PRNGX%+2:ASL A:ASL A:ASL A:ASL A:ASL A:ORA PRNGO%+3:STA PRNGO%+3
 4770 \ XOR
 4780 LDA PRNGO%:EOR PRNGX%:STA PRNGX%
 4790 LDA PRNGO%+1:EOR PRNGX%+1:STA PRNGX%+1
 4800 LDA PRNGO%+2:EOR PRNGX%+2:STA PRNGX%+2
 4810 LDA PRNGO%+3:EOR PRNGX%+3:STA PRNGX%+3
 4820 \ shift right 17
 4830 LDA PRNGX%+2:ROR A:AND #&7F:STA PRNGO%
 4840 LDA PRNGX%+3:ROR A:ROR A:AND #&80:ORA PRNGO%:STA PRNGO%
 4850 LDA PRNGX%+3:ROR A:AND #&7F:STA PRNGO%+1
 4860 LDA #0:STA PRNGO%+2:STA PRNGO%+3
 4870 \ XOR
 4880 LDA PRNGO%:EOR PRNGX%:STA PRNGX%
 4890 LDA PRNGO%+1:EOR PRNGX%+1:STA PRNGX%+1
 4900 LDA PRNGO%+2:EOR PRNGX%+2:STA PRNGX%+2
 4910 LDA PRNGO%+3:EOR PRNGX%+3:STA PRNGX%+3
 4920 \ shift left 5
 4930 LDA PRNGX%:ASL A:ASL A:ASL A:ASL A:ASL A:STA PRNGO%
 4940 LDA PRNGX%:ROR A:ROR A:ROR A:AND #&1F:STA PRNGO%+1
 4950 LDA PRNGX%+1:ASL A:ASL A:ASL A:ASL A:ASL A:ORA PRNGO%+1:STA PRNGO%+1
 4960 LDA PRNGX%+1:ROR A:ROR A:ROR A:AND #&1F:STA PRNGO%+2
 4970 LDA PRNGX%+2:ASL A:ASL A:ASL A:ASL A:ASL A:ORA PRNGO%+2:STA PRNGO%+2
 4980 LDA PRNGX%+2:ROR A:ROR A:ROR A:AND #&1F:STA PRNGO%+3
 4990 LDA PRNGX%+3:ASL A:ASL A:ASL A:ASL A:ASL A:ORA PRNGO%+3:STA PRNGO%+3
 5000 \ XOR
 5010 LDA PRNGO%:EOR PRNGX%:STA PRNGX%
 5020 LDA PRNGO%+1:EOR PRNGX%+1:STA PRNGX%+1
 5030 LDA PRNGO%+2:EOR PRNGX%+2:STA PRNGX%+2
 5040 LDA PRNGO%+3:EOR PRNGX%+3:STA PRNGX%+3
 5050 PLA:TAY
 5060 PLA:TAX
 5070 PLA
 5080 RTS
 5090 ]
 5100 NEXT
 5110 PRINT"RNG ";(P%-PRNG%);" bytes"'
 5120 ENDPROC
 5130