Resource centre for ZX Spectrum games
      using Manic Miner and Jet Set Willy game engines

 

 

Previous message		Next message

 

 

Message: 6482

Author: andrewbroad

Date: 20/10/2008

Subject: Re: Ma jolie – Game-engine bug

 

Sorry, tennis - looks like I have a MM-distraction on my hands! ;-)


Daniel wrote:

>
> Andrew Broad wrote in the text file included with the game,
> concerning "The Hot Room" (01):
>
> (snip) "Oh, and there's a sneaky trick to make you have to go all
> the way round again after collecting the 'last' item."
>
> In fact, you do NOT have to go all the way round again at all.
> Download the walkthroughs to see how it can be done :-) .

I believe most players would have to go all the way round again, and
I'm happy to let them believe that, while others may find the optimum
route. I don't feel inclined either to edit the room or add a spoiler
to README.TXT.

> Andrew wrote in the text file included with the game,
> concerning "The Mad Ramblings of Longbeard" (05):
>
> (snip) "It's up to you whether you want to 'walk the plank' before
> or after you jump across the crumbling clouds, " (snip)
>
> In fact, you do NOT have to jump across the crumbling clouds from
> one end of the room to the other, and afterwards (or before) 'walk
> the plank'. You can get the rightmost item separately and
> afterwards (or before) jump across the crumbling clouds and drop
> down onto the ship, so that you 'walk the plank' only one way
> (saving some time).

Wow: I didn't know you could do that!

I'm not sure I like the look of this, and I'll have to meditate on it
before I decide whether to close this loophole or let the player who
discovers it feel clever.

> This involves using a quirky feature of the game engine which has
> to do with jumping off the top of the screen. I don't really
> understand how it works; I just know, by trial and error, that it
> does. I am pretty sure that it (or a similar, related feature) has
> been exploited (purposefully) in "Manic Scribbler" (in various
> rooms, I believe) and I have seen it happen (though not used
> purposefully) in the room "GoldenEye" (16) in "JSW64 Manic Miner:
> James Bond" (see messages # 6355, 6356 and 6357).
>
> Unfortunately, it also involves – I believe – the jumping-off-the-
> top-of-the-screen bug which tramples over memory when you fall off
> the bottom of the screen or jump up off the top, with the curious
> result that if you proceed this way in "Ma jolie" (either edition)
> the game becomes impassable later on, while in "Ma jolite" (either
> edition) you can still complete the game and (by saving time) boost
> your final score by over 100 pts.!
>
> Now, I assume the problem is the jumping-off-the-top-of-the-screen
> bug. However, I cannot quite discard that the problem may have
> something to do with the phenomenon whereby standing on a Crumbly
> cell in row 0 o 1 causes the cells in row 8 or 9, respectively, to
> crumble.

You can discard the latter theory. It is documented in my Manic Miner
Room-Format (Offsets 0 to 511: Screen-Layout) that jumping off the
top of the screen, or falling off the bottom, corrupts the screen-
layout of Room 7 in the Bug-Byte engine, or the guardians in Room 8
in the Software-Projects engine.

> The jumping-off-the-top-of-the-screen bug has been described in
> detail (also technical) by Andrew in the "Technical Notes" on his
> 2004 game "Manic Miner: Neighbours - Allana Truman" (included with
> the game file). Andrew actually fixed the bug in Room 7 of that
> game.

It's a shame I didn't apply that patch to Ma jolie when I had the
chance, since MM:N-AT predates the Special Edition of Ma jolie.

I suppose I'll have to 'omega-release' (there's a term I thought I'd
never get to use!) Ma jolie at some point, now that this bug has been
discovered. (Note to self: didn't I forget to fix something else when
I Special-Editioned Ma jolie?)

> In "Ma jolie" the intriguing thing is that the corruption is not
> visible either in the room where the bug happens ("The Mad
> Ramblings of Longbeard" [05] - unless the crumbling cells 8 rows
> below have something to do with it) or in the following room 06
> ("The Vatican") and then it suddenly shows its ugly head in room 07
> ("Ape-Men with Metal Parts")!

This is what you get with a bug that calculates erroneous write-
addresses from out-of-range indices. It's the same with the invalid
arrow in Jet Set Willy's "The Attic", which tramples over the
guardian-class table, affecting various rooms.

I have yet to determine whether jumping up off the top, or falling
off the bottom, of a JSW64:MM game with my "Disabling the room-exits"
patch from JSW64MM: James Bond applied, has any similar harmful
effects. That's why I designed James Bond v1.0 so that the tops and
bottoms of the screens are always blocked... except for the
unintended loophole in "The World Is Not Enough", which I intend to
fix for v1.1. I might also have to consider adapting my bug-fix from
MM:N-AT for JSW64.

> In "Ma jolite" I didn't notice any further corruption after the
> room "Ape-Men with Metal Parts" – the game can be completed. After
> passing the final room ("Heathen (The Rays)") I played on to see
> what would happen. "The Mad Ramblings of Longbeard" didn't have any
> corruption. I solved it in the traditional way and went on to "Ape-
> Men with Metal Parts" to discover that the corruption was still
> there! It was as harmless as before. You can see this test in the
> file "jolly_jolite.rzx" in my folder in the Files section of the
> Group.
>
> I don't know what happens in "Ma jolie", since one cannot progress
> beyond "Ape-Men with Metal Parts" after the bug has occurred.
> I would assume it remains there, just as its equivalent does in "Ma
> jolite".

Only Room 7 of a Bug-Byte-based MM game is affected, as previously
stated.

> Now, a suggestion for an utterly-sophisticated game designer:
> design a game in which, if you solve room A in the traditional way,
> two rooms later (in room C) you encounter an obstacle which makes
> the game impossible to complete. However, if you complete room A
> causing the jumping-off-the-top-of-the-screen bug, the obstacle in
> room C is there no longer, because the bug has made it disappear
> :-) .

That would be way unfair, especially as the changes caused by the bug
are permanent! Such challenges would be better achieved using patch-
vectors, such as the one in Geoff Eddy's _Willy Takes a Trip_ (IIRC),
where collecting all the items in one room causes a wall to disappear
in another.

Anyway, I haven't even touched MM/JSW in recent weeks, as I'm
currently putting all my Copious Free Time into finishing my
Wimbledon-reports, which I will finish in early November. Then the
2008 tennis-season will be over, and I'll have fewer tennis-
distractions. I'll still have to update the biographies of my players
before the end of the year, but I'm also determined to work on James
Bond v1.1 and JSW64: Flash MM in November and December, with a view
to gamma-releasing them at the end of the year, even if this will mean
breaking a near-promise to the Lucie Šafárová community.

2008 has been very hectic in tennis-terms, as my decision to write
JSW64MM: James Bond in time for a 2007 release caused a massive
tennis-backlog to accumulate. I'm optimistic that I will be able to
redress the balance between tennis and MM/JSW in 2009.

--
Dr. Andrew Broad
http://geocities.com/andrewbroad/
http://geocities.com/andrewbroad/spectrum/
http://geocities.com/andrewbroad/spectrum/willy/

 

 

	Back to the Yahoo! Archive
Previous message	home page	Next message