CSB Challenge - Items remaining

[Kuolgs]

I did it!
https://ibb.co/18T7zQ3
This is not the first time I try to clean the dungeon as much as possible but I had never cared about removing all monsters. In the process I also discovered a few items I did not know of (an iron key in a crack in ROS for example). The only serious issue I got was a crashed savegame for some unknown reason. Neither did I find a way to clean the upper level from all demons while going to the FulYa pit, so I had to wait some time that the newly created demons were killed by the fireball launcher.

And of course, I did my best to keep the fountain room reasonnably tidy.
https://ibb.co/mt8PPrj
https://ibb.co/xHg1cX6
https://ibb.co/PFBYX9b
https://ibb.co/WcmdGZf
https://ibb.co/ChTx1Sq
https://ibb.co/TLTjXQZ

[Paul Stevens]

Congratulations. You have mastered Chaos Strikes Back as few others have done.

Sorry about the crash. Hopefully these are relatively rare.

[Antman]

Congrats! Yes I don't think many others have done so, it's a tough challenge.

I think for the demons one you spawn them you have around 20 seconds to blow them up and get back through the master key door without spawning more.

I haven't seen a crash for a long while in CSBWin. I think Coatls stopped making an attacking sound for some reason though.

[Paul Stevens]

Wow....I just cleaned out the Chaos Strikes Back dungeon. I had forgotten
what a difficult task this is. I did not do any planning whatsoever and I
wound up going through most of the dungeon many times. Particularly
frustrating was the entry to the upper Neta area (the skeleton puzzle
below DDD). I had to set it up twice and had to make my way past that
door at least five times! Setting it up requires going through the Mummy/Prison
and I had already killed all the Mummies.

At any rate, I made a recording of my successful sweep.

https://dianneandpaul.net/CSBwin/CSBSweep_996Minutes.7z

In fast-play mode you can watch it in about 55 seconds.
It took me over 16.6 hours.
As far as I know, that is a record - 996 minutes. Did any of
you folks make a recording of your attempts?

[Antman]

I made this one a couple of years ago https://drive.google.com/file/d/186S8rA ... drive_link, 3h 58m 38s and 5 sixth-seconds.

Though according to the readme I edited the dungeon to prevent the teleporter bug (moved 07(14,30) teleporter destination to 08(14,36)). I also allowed duplicated timer entries to prevent the other teleporter bug (stop an EE potion being left at 07(14,34)), but maybe that didn't work IIRC. So I guess it's not a legal recording. I also used saves and spliced the recording together, I guess you did too? Otherwise 16 hours is quite the effort!

I planned a lot of it out to minimize killing monsters and repeating areas, though I think I spent a bunch of unnecessary time training ninja with some rockpiles. Definitely room for improvement, four champions would be faster than two.

[Paul Stevens]

No...Your record should stand. For now.
Bugs...
07(14,30) -- I'll add this location to the list of exceptions.
Duplicate Timers -- The default I believe.
07(14,34) -- Already listed as an exceptional location.
Saves/Restores -- Allowed, certainly.

I could not get your recording; I asked for access. I'd like
to add a folder to my CSBWin web-page with the challenge itself
(I'd turn on 'auto-record') and any successful recordings.
May I put yours there?

[Antman]

Oh actually 07(14,30) doesn't need to be in the list, the items that go through that teleporter (fired by the shooter at 7(14,34)) are normally teleported to 7(09,30) then fly north, hit the wall and rest at 7(09,26), becoming stuck forever. 7(09,26) is already in the exceptions list I believe. Anyway, I considered this a bug in the original CSB and it annoyed me they would be inaccessible, so I changed the teleporter to send the items to a different, accessible, location.

With 07(14,34) if two Gigglers hit the pressure pads triggering the shooter, the EE potion can become stuck forever, so I turned on duplicate timer entries to prevent this as I thought it wasn't the default. But the EE potion may have remained stuck anyway, meaning something else caused it not to fire...

Sorry about the access, anyone should be able to access it now with the link above. And yes please feel free to publish anywhere

[Sphenx]

Considering the design of this chaotic randomness, I genuinely think 7(14,30) is not a bug but a "you'll never get that one". For the multiple triggering at the same time, maybe they did see it but did not care to solve it. Maybe the gigglers would have require to get through a corridor to prevent this. As a note, only the the eight pits traps has been reused as randomness design in Theron's Quest.

[Antman]

Could be, but the randomness of the where the teleporter goes (why to the middle of the inaccessible teleporter room?), plus the fact all the other items are accessible, and that it could be the dragon shield or helm of RA that gets stuck preventing from completing the dragon and RA sets, or boots of speed preventing getting all four, makes me think it's a bug. It's also difficult to detect during playtesting so easy to miss. I'm also not sure how they handled the level offsets but maybe the desired location is the same co-ords but on another level. I chose the vexirk room on the level below.

Also another (almost certainly) bug exists where the teleporter at 7(14,33) is never hit with an item, it gets turned off too quickly I believe. So the item flies to the last teleporter and you end up with two items at 2(12,08) and none at 2(14,20). Which shows that this particular setup already had at least one other bug.

Impossible to be sure though. Maybe ChristopheF would have an idea since he knows a lot about the code, dev team, background etc. to have a good "feel" for what is a bug and what is not. Or if it was fixed in any later version.

[ChristopheF]

I have no idea if this is a bug or if it was a deliberate design choice to make some items unreachable by the party. There are no clues in the code as this is only defined by the dungeon data itself.

[Sphenx]

Don't think too hard about this ... We'll probably never know.

Also another (almost certainly) bug exists where the teleporter at 7(14,33) is never hit with an item, it gets turned off too quickly I believe. So the item flies to the last teleporter and you end up with two items at 2(12,08) and none at 2(14,20). Which shows that this particular setup already had at least one other bug.

That one is interesting, because checking the dungeon data, it seems that values for delays/ticks are OK and proportional to the distance of each teleporter. Then if it does not work as expected, it might be a bug in the engine ? Is this something that happens every time or on specific condition ?
I am not yet expert enough in actuators + timers to correctly understand what happens : when one pad at 7(12,26) to 7(12,33) is stepped on, does the shooter trigger on the same tick (and items are already over tile 7(14,33) on tick 0) or at tick + 1 ?
I also wonder what happens if we play this dungeon with PC-DOS version or even DM2 engine ...

[Antman]

Good question, maybe the process for each tick is move flying items, toggle teleporters, shoot items. So moving items are correctly teleported on the same tick but items out of a shooter are not (assuming things are shot at tick +1). This bug occurs every time, at least in CSBWin.

I guess Paul can answer why this particular bug occurs and if it's specific to CSBWin or not.

I could try on the Amiga version and see I guess... Though I don't think I remember seeing items at 2(14,20).

[ChristopheF]

In the 'Solutions' section at the end of the Chaos Strikes Back Adventurer's Handbook (http://dmweb.free.fr/?q=node/406), a "random item" is listed at each target location of teleporters, except at 2(14,20). So I guess the teleporter does not work even in the original game (but I have not checked/tested).

[Paul Stevens]

If you want to study particular timing problems the most
help would come from duplicating the problem with timertrace
active. The traces are a bit difficult to interpret but the
information you need is all there. I'd be happy to help with
the interpretation if you were to provide the trace.

[Sphenx]

I have made some testing -- basically accessing this particular area -- with some adaptation to make pads and teleporters visible.
I tested it with DM and DM2 PC-DOS versions and I've done some recordings to show what happens.
Record 1 : DM PC-DOS
Record 2 : DM2 PC-DOS

It seems that all versions behave the same, and it looks like a bug in the engine for me.
What happens is that at tick 0, item is shot and teleporter also gets on, but apparently, the teleporter check is not done for the item, then it continues its flight towards the last teleporter.



Then this teleporter actually never worked. Since its target is not listed in the "Solutions" pages, that means they found it out, but probably after the dungeon was already released.
An easy fix is to delay 1 tick both open and close teleporter, and it will work as designed.

[Paul Stevens]

The CSBwin code, in the "LaunchMissile" function, contains
the following comment:

Code: Select all

  //
  // **************************************************
  //
  //  We really should check to see of the room contains
  //  a teleporter that affects this missile.
  //  'AddObjectToRoom' does not check.
  //  'MoveObject' does check be we cannot use it.

I have no notion of how this comment came into being.
There is no way I could have been clever enough to foresee
this problem. At any rate, the code only checks for
teleporter action when the missile enters the room, not
when it moves within the room and the shooter code
forgets to check. That is how it was and it survived into
the Chaos Strikes Back code for the Atari.

What does DSB do? RTC?

We could change it but it would be a delicate operation
because I have forgotten much of what I once knew about
the CSBwin code and because there would be little testing.
It would require a great deal of persuasion.

[Paul Stevens]

An easy fix is to delay 1 tick both open and close teleporter, and it will work as designed.

I think the following is true:

The standard engine cannot guarantee the order of timers that
expire on the same tick of the clock. But I believe CSBWin has
been modified to ensure that timers are processed in the same
order that they are created. So, for CSBwin, it is not necessary
to change the times. Simply change the order that the timers
are created by changing the order that the pressure pads are
processed. And they are processed in the order listed in the
CSBuild editor. Then the object will already exist within the
teleporter when the teleporter is activated and all will be well.

This also means that the standard engine should work about half
of the time whereas CSBWin will never work with the dungeon as it is
currently designed.

[Antman]

Interesting to hear how it works. I don't think it's necessary to try and fix since the items are still accessible. It would mean it's possible to complete the game with 3 keys + boots of speed + 4 corbums as an alternative for the items challenge.

Anyway, I'm interested to make a better CSB challenge recording so should use a non-edited version of the dungeon. Just need to find the time...

[Sphenx]

Simply change the order that the timers
are created by changing the order that the pressure pads are
processed. And they are processed in the order listed in the
CSBuild editor. Then the object will already exist within the
teleporter when the teleporter is activated and all will be well.

Thank you sir for the explanation; I have changed the order of the actuators so that the shooter proceeds before teleporter opens. Although I was expecting it to work from your explanation, it seems not and item still flies away. Still not better for DM PC-DOS and DM2. I might now dig more into the code.

[Sphenx]

I made some mistake somewhere. Changing the order actually works for DM2.

[Paul Stevens]

I made some mistake somewhere. Changing the order actually works for DM2

DM2??? Is there a DM2 dungeon for CSBwin?

Changing the order might or might not work with other engines. It
is an implementation issue; what algorithm is used to sort the timers.
The original Atari code randomized timers with the same expiration.

[Sphenx]

DM2??? Is there a DM2 dungeon for CSBwin?

It is the other way, CSB dungeon for DM2. For what it's worth, you can try my pseudo-conversion here CSB for DM2 (test). It starts specifically in the gigglers room to test the pads/teleporters. It actually confused me because the specific teleporter we talk about is randomly working in DM2! maybe the code reverted back to the original code you talked about ? I added a teleporter around to go in the DDD room where items are supposed to be teleporter to.
(You can try to explore more around in CSB-DM2. With no warranty).

[Antman]

I finished making a recording of the CSB Challenge, this time with a non edited dungeon. I took four characters. It took 2 hours 25 minutes 26 seconds and 4 sixthseconds, though I spent some time opening extra doors, cleaning up food and monster drops that don't count for the challenge. Not too much longer than my first speed run recording!

You can find the recording here https://drive.google.com/file/d/1C51XQF ... sp=sharing.

Enjoy!