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Message: 6433

Author: andrewbroad

Date: 18/05/2008

Subject: Re: Mirror MM/JSW / MM<->JSW Conversions

 

Daniel wrote:

As part of the process of playing and RZX-recording all of the
gamma-released MM/JSW and MM/JSW-related games, I have just
completed Andrew Broad's laterally-inverted MM and JSW and the
mutual conversions between these games, released as parts of
the "Party Willy" box-set (2004, Special Edition 2007 -
http://www.geocities.com/andrewbroad/spectrum/download/) . Here
are some comments about things that caught my attention.

1. Laterally-inverted MM and JSW

In "reniM cinaM" I noticed various instances of the cell-graphics
bug (formerly known as the block-graphics bug), (at least) in
rooms # 00, 07, 11, 12, 15 and 19 (this saves me quoting their
weird names! :-) ). I presume that their appearance is a side-
effect of the lateral conversion.

Correct.

A question to Andrew would be whether the inverting algorithms
should not take that into account and eliminate the bug? And,
similarly, make sure that the cell-graphics bug is present in the
conversion if it is present in the original version (so that all
cell graphics are preserved, although inverted).

having resisted the temptation to fix the bug. I would just say it is an element which is very visible to someone familiar with MM>

Yes, I decided against having the mirroring-algorithms patch the
games, as this would lose the property of reversibility
(Mirror(Mirror(x)) = x), and would also entail the problem of finding
free space to put the patches:
- finding free space may be impossible if there is none left;
- proving that a given range of addresses is free is, in general,
undecidable (since it may reduce to the Halting Problem).

It's most intriguing to see cell-graphics that differ from what you'd
expect, due to the Cell-Graphics Bug being asymmetrical. Sometimes
mirroring actually 'fixes' occurrences of the Cell-Graphics Bug in
the original JSW, so you see the graphics as Matthew Smith drew them!

In "ylliW teS teJ" I noticed that there are some things which are
not inverted, such as ropes or arrows (or so it seems, at least).
This creates some differences with the original in the gameplay. I
had a nasty surprise when I discovered that you cannot climb down
from "rewoT hctaW" ("Watch Tower"), because the rope in the room
below keeps throwing you upwards, back into "rewoT hctaW". So I
couldn't take what I consider to be the most effective route
around JSW (climbing down from "Watch Tower" after collecting the
items and later exiting upwards in "Rescue Esmerelda"), and I had
to use the second most efficient route, which involved re-
recording most of the game!

Arrows are perfectly reversible: a start-column of x maps to 287-x
(as proved in Message 1867).

Ropes start at a different place in the swing when going right
initially as opposed to left. I should look into this further one day.

Another interesting and visible difference is that you cannot drop
down onto the platform below, at the last moment avoding the HG,
in "fooR yrotavresnoC" ("Conservatory Roof"), which you can do in
the original JSW. Thus, you cannot exit downwards and you have to
look for an alternative way of collecting the topmost item
in "yregnarO" ("Orangery").

Still another example would be that you cannot jump straight up
between the two guardians on the middle platform in "yebbA
nettogroF ehT" ("The Forgotten Abbey"), on the first approach, the
way you can in the original, which slows you down just a little
bit.

Horizontal (and diagonal) guardians cannot be perfectly inverted,
because in JSW, they always start on their leftmost sprite-frame,
regardless of whether they go left or right initially (see Message
6340 for further discussion of this issue).

2. Conversions between "Manic Miner" and "Jet Set Willy"

The thing that struck me most about these conversions is the
difference between them in the sense of the quality of the final
result. Most of the rooms from JSW transferred to the MM game
engine are very dull - the gameplay is simply horrible due to a
virtual lack of challenges, the ability to leave the screen on one
side and re-enter it on the other side, fall down and re-enter the
screen from above and avoid death by falling (from higher than
four character rows) into a flashing portal. The game could almost
qualify for the Crap Games Compo :-) . Please note that this is
not criticism of the conversions -it's very nice to see them, and
they are very instructive. Or actually - do the conversions just
seem so dull right after playing "JSW64 Manic Miner: James Bond"
:-) .

I've always found it most intriguing to play the JSW rooms in MM,
despite the limitations imposed by the game-engine. And it's fun to
have some easier rooms to be able to play through quickly for once.
MM:JSW is only a titbit, and should not be judged by the standards of
a feature-game.

The downside is that I had to commit the player to crossing each room
only in one direction, and faced some awkward decisions about which
direction that should be. It was also awkward to decide which
guardian-sprite to use for each room, since the MM engine doesn't
allow you to mix them in a room.

It would be an interesting project to reinterpret the JSW rooms for
MM - even as a JSW64 game with portals and no way to touch the edges
of the screen, so that the restriction on guardian-sprites is lifted.
Not as a faithful conversion, but as a quality MM game.

Likewise, you could reinterpret the MM caverns for JSW - not as a
linear game with portals, but with similar connectivity and lack of
walls as the original JSW.

On the other hand, MM rooms fare much better in the JSW game
engine, IMO. It is a very nice feeling to be moving around in a
JSW world full of MM environment. The lack of time limit and
crumbling floors does effect the attractiveness of the rooms, but
there are some nice challenges -it took me a while to figure out
how to solve "The Warehouse", because I didn't realise the two
green flowers were a ramp. And the downwards exits back to the
preceding rooms in the form of one-block ramps are a nice
solution, too.

A technical details that caught my attention is that there seem to
be some minor differences between the game engines you don't
normally think about. For example, in the real MM, in "Wacky
Amoebatrons" it is possible to walk beneath the green VG if you
hold the Right key since (before) the moment you "enter" the room.
However, in the same room transfered to JSW the trick is no longer
possible - the green nasty amoebatron kills you if you don't stop
before it.

It's not a difference in the game-engine - you just start further to
the left in the JSW:MM version of "Wacky Amoebatrons".

But there /is/ a difference: MM allows you to specify the start-frame
of each VG (0, 1, 2 or 3), whereas in JSW, a VG's initial start-frame
is always 0 (before the start-frame mask and animation-mask have been
applied - you can't have a smooth cycle if you have a start-frame
mask other than 0 or 4).

Thus all the amoebatrons start on the same sprite-frame in JSW:MM,
whereas in MM, they start on four different sprite-frames. The
perfect solution would be a very expensive one: to have four copies
of the amoebatron-sprite, each with different sprite-frames in
different sprite-frame numbers. It's hardly worth it for a difference
that only the most observant players would notice.

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

 

 

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