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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/

 

 

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