Jet Set Willy 2021 Edition (for the BBC Micro)

[TobyLobster]

I've improved the BBC Micro version of Jet Set Willy. The disk image and description of my changes are here https://github.com/TobyLobster/jsw2021

Play in a browser: http://bbc.godbolt.org/?autoboot&disc=https://raw.githubusercontent.com/TobyLobster/jsw2021/main/JSW.ssd

(Previously I improved Manic Miner for the Beeb, see https://github.com/TobyLobster/ManicMiner2021)
 

[Spider]

Wow that is excellent 😮 😮  top class work.

I can't say anything more other than the in-game tune is excellent too, I was not sure when I was reading the description quite how it was extended and enhanced but I hear now 😉 😄

EDIT... You have a PM about two things too 😉

[Spider]

Quick notes: I see you've carefully retained the Kitchen guardian paths so you can move leftwards without stopping, something other versions sometimes forget.

The Swimming Pool item auto collects (expected) as well as retaining the charm and quirks of the original, I can imagine it was (if it was me) difficult to not want to 'fix things' , but as they say if its not broken don't try to fix it. 😄 🙂

I'll stop posting now to not spoil it

[TobyLobster]

Yes, it always bothered me when you couldn't run straight through from right to left through both Kitchens. It was a toss up whether to 'fix' The Swimming Pool, but as the code was already there to do it I thought that was maybe better to preserve it than to lose it.

[Norman Sword]

reference  TobyLobster/jsw2021    from GitHub

Quote:-

Documenting the Remaining Minor Differences

• The jump parabola shape is very slightly different (while still being the same height and length overall) since the code seems to have problems with odd numbers of pixel height changes within the jump. This makes only a few minor changes overall:
  • Nomen Luni: On the BBC you can jump from the top of the slope, under the Moon enemy to land on the platform under the ledge. On the Spectrum you have to jump to the lower platform first.
  • The Bow: to jump up from the platform next to the wheel item needs two platform tiles instead of just one.
  • Top Landing: Jumping into the Chapel area lands on the top level of flooring not the tiles below as on the Spectrum.
• The Forgotten Abbey: The platform under the item should be a wall, but changing this means the player can't fall down past it, trapping them at the top of the room.
• All the differences above match what is seen in the Spectrum's JSW II, so I imagine the jump parabola there matches the BBC version.

A correction to the above statement- highlighted in red. JSW II uses the correct parabolic data. The reason -The Bow-, has two blocks instead of one in JSW II is the consequence of JSW checking the wrong blocks. This also causes the bug of passing into floors when jumping in -the First landing- going towards -the Chapel-.  The code in JSW does not handle the double crossing of block edges, when entering a new block diagonally. That is when it moves both vertically and horizontally across a block boundary. This also is the reason why JSW II can clear the wall in the Garden and the same move is impossible with the code of JSW. 

 

Edited July 23, 2021 by Norman Sword
Correcting logic. Correcting data.

[TobyLobster]

Oooh, that's good to know thank you. I've updated the document to remove my incorrect guess.

[Spider]

I have now ( with thanks to @TobyLobster ) submitted the file here now too.

Download > https://jswmm.co.uk/files/file/148-jetset-willy-2021/

Discussion Topic (auto generated by a new submission) > https://jswmm.co.uk/topic/623-file-jetset-willy-2021/

🙂

 

[IRF]

The quirks relating to the jumps referred to above in JSW occur because, in each increment of a jump cycle, Willy is moved vertically before the check is made as to whether there is a standonable cell underneath him.  (Logically, you might expect the check to be made before the move.)  Then horizontal motion is dealt with later in the jump cycle: if Willy is about to pass horizontally into the next pair of cell-columns, there is a check for solid blocks immediately ahead of him, and if not then he is moved sideways.  The net result means that he can fall down into solid blocks during the descent of a sideways jump at a certain angle, especially if there is a solid wall to the right of his head (which 'guides' him into the situation, as per the approach to The Chapel).

The combination of the above also means that he can't jump sideways into a channel between solid blocks, so Matthew fudged that by removing the check for head-height solid blocks to Willy's left only.  That fudge allows him to access the items in the left-hand side of the Wine Cellar, which would otherwise be unreachable (and also to jump back over the barrel in Ballroom East after returning from the top of Front Door.  In a laterally inverted game, Willy lands on the floor where he is supposed to in the approach to The Chapel, but the Wine Cellar is impossible to complete.

[TobyLobster]

Thanks IRF, very interesting. That's an interesting quirk of the implementation. There's some deeply knowledgable people here it seems!

[Spider]

This is why in say " YlliWTeSTeJ " , there's an extra couple of water cells*** to permit M.W to jump across properly, see my combi pic. Please ignore the fact the guardians are not in the exact same places, did not see a need to go that far 🙂

You can clearly see those red water cells in the 'mirrored' / 'inverted' one though as M.W is stood (in the right hand pic) a block away from them.

*** More accurately really two earth cells were replaced with water, allowing him to 'pass his head' through 😄