And, perhaps, lack of coherent instructions. The rumours on previous Stardot threads were that it's "impossible to complete", but I'm sceptical of how anyone would know this for sure, I don't see a full explanation other than some mumbling about "impossible to get the green key", and I've been looking at the code trying to work out whether it's really true.
Specifically, it's clear why one would think the game is impossible from looking at the map. The giant's dining room (column 4, row 3, just below the room with the seven doors) is the climax of the game, where you obtain the green key that will unlock Jill's prison. But the only way to get into that room is from the room above, which requires you to pass through seven doors, including a green door. What I am now sure of, though, is that from the game's point of view there are two different doors which both happen to be green, and the one in the seven-doors room is unlocked not by collecting a matching key but by reaching a score of 83 (i.e. collecting 83 objects).
I have a vague recollection of actually doing this BITD once, using an infinite-lives cheat. Today with less patience but better tooling, I have been able to visit the dining room without collecting 83 objects (see cheats below). When you collect the green key in the dining room a timer starts ticking down and you lose the game if it gets to zero: this seems consistent with the vague game inlay instructions ("You'll have to collect all the fruits and bits and pieces on the way and finally when you've found THE key you will wake up that old meany, the Giant. He's down on you like a ton of bricks and you will only have 2 minutes to race back through the castle and out to freedom.") The existence of the timer code also seems to confirm that something is really meant to happen here and it's not just all the inlay-writer's fantasy.
However, I can't work out what to do next, because I still can't find any way out of the dining room. You can't jump high enough to get out the way you came in, and dropping through the otherwise-tempting hole in the floor seems to be a fatally long fall. So as of now, I'm still stuck.
References:
Screenshot map on stairwaytohell.com.
Sutty's posts fixing some crash bugs in Jack Attack: 1 (contains explanation of fixes), 2 (contains corrected version of game image).
Jack Attack on bbcmicro.co.uk (I am working from this image. It contains a version of Sutty's fix for the crash bug, but doesn't include Sutty's Master-compatibility fix.)
Inlay instructions on everygamegoing.com. Sorry Dave for deep-linking an image; I can't figure out how to navigate through the JS otherwise.
Appendices:
Cheats for the bbcmicro.co.uk version of the game:
Code: Select all
LO."SHFT"
161?&4976=&A5: REM infinite lives
162?&4A7B=&FF: REM unlock all doors except Jill's cage
163?&4A88=43: REM start above the seven-doors room
164?&4ACF=0: REM giant's timer speed (default value is 11)
165?&46C8=&30: REM invulnerable to long falls
166?&4789=&10: REM invulnerable to monsters and trees (warning, glitchy and you can walk into killscreens)
RUN
Code: Select all
1A76 F8 SED
1A77 AD FE 2E LDA &2EFE
1A7A 18 CLC
1A7B 69 01 ADC #&01
1A7D 8D FE 2E STA &2EFE
1A80 D8 CLD
1A81 C9 83 CMP #&83
1A83 D0 0A BNE &1A8F
1A85 A9 00 LDA #&00
1A87 85 8B STA &8B
1A89 A9 FC LDA #&FC
1A8B 85 F3 STA &F3
1A8D A9 10 LDA #&10
1A8F 4C 45 1A JMP &1A45