IRF

I think the observation might have consequences for how quickly Willy can complete the cavern in Manic Jet Set Willy, compared with original Manic Miner. By only having to take one step forward (not two) off the upper platform (onto the upper crumblies) before dropping and then jumping leftwards to collect the final (lower-right) item, you can collect that item one air-increment sooner and then head to the portal - gaining one extra point for this cavern. There may be other caverns where the ability to step one increment closer to a Fire cell embedded in the platform you are standing on before jumping over it could gain you more points. However, I can't think of another scenario in the original MM caverns where there is a Fire cell underfoot in this way and a time saving may be gained; most Fire cells are at knee-height or are overhead. Maybe The Vat or The Warehouse might play out differently? EDIT: In the JSW room The Beach, it might be possible to get closer to the crabs before jumping over them without being nipped.

Note to self: I will have to check whether this Endorian Forest discovery has any implications for a certain project of mine... EDIT: I mean for the game engine, as well as for the data.

I've just rewatched Crem's walkthrough of The Vat. When Willy first starts walking behind the pink kangaroo, he is so close to it that I suspect he might have collided with it when trying to jump up to the next platform as it turned around at the end of its trajectory. The early jump whilst walking along probably prevented that, by setting him back a step relative to the kangaroo (for the reason I mentioned earlier - the last step of a sideways jump doesn't actually move him sideways). However, he could have achieved the same thing by simply stopping walking for one time-frame (which, as you say, would have been slightly quicker in real-world time).

If Willy is walking sideways and does a jump (landing on the same level), then the last frame of animation of that jump he drops down vertically, so his sideways momentum is slowed down ie it costs time both in terms of air supply (one increment) AND slower execution of the program during the jump. I can't think of a scenario where jumping might be 'optional' in the way that you suggest in MM? (In JSW, you can allow an arrow to pass through you rather than jump over it if there happens to be some non-solid platform that Willy can hide inside/behind when the arrow passes through him.) You're right about the first Kong, of course - I was thinking about the second one and completely forgot about the first!

Point 1: makes me wonder if the current optimised routes (because of the way they were created) didn't consider the possibility of pressing turn-around-and-jump-again during a jump, and whether there are any further efficiencies to be found elsewhere as a result? EDIT: Although I've just noticed that Willy does precisely such a manoeuvre halfway through the AI walkthrough of Wacky Amoebatrons, for example. With the immediate benefit of allowing Willy to get up onto the next level of WA slightly quicker. The Endorian Forest example may be unique because the turn/jump move is 'time-neutral' when considering the rate of progression through the cavern on a 'localised' basis; the one time-frame efficiency is only realised later on, when Willy comes to drop down again, and it transpires that the remnant of the crumbly platform lends itself to a slightly quicker descent. Point 2: I seem to recall that the objectives of fastest completion and highest score are nearly always in perfect alignment in Manic Miner; the only exceptions being the flicking of the switches to dislodge Kong Beast (for extra points, at the cost of one more time frame), and the Solar cavern (due to the need to minimise contact with the beam to reduce air sapping and thus increase the end-of-cavern score). So I don't foresee any difficulty in updating the data stream for The Endorian Forest.

Couple of things: (1) The program does react to keyperesses in certain circumstances even when the Airborne Indicator is set - namely when Willy lands after a jump up onto a platform higher than the one he jumped from. This allows him to land, turn and jump again in a single time frame. Indeed, that is the very manoeuvre which allowed you to gain an extra point. (2) There is already a datafile for the previous best performance available earlier on in this thread (Crem provided one for each cavern). So I think the easiest thing to do would be for me to scrutinise the few frames where the new route differs, and manually edit the data accordingly.

I was thinking along the lines of the format in the first post of page 6 of this thread, where a full stop indicates no movement keys being pressed for one time frame, with other movement keys being indicated by letters. Norman Sword wrote a program which automated the optimised sequences of keypresses (or lack of keypresses when appropriate), to create a version of Manic Miner which plays itself to a maximum final score (or, as it turns out, at least one point shy of the maximum possible score). You can also select BB or SP version to watch the automated optimised routes in action.

I wonder if someone updated the keypress datastream for The Endorian Forest (I could have a go myself although I'm about to fly off to Nice), whether @NormanSword might consider updating his game file which consisted of automated optimised routes through the caverns, to take account of this new discovery?

Although now that I think about it, I've already done an in-depth analysis of how to descend through a field of crumblies (a technique which is needed most notably in The Vat and The Warehouse in order to maximise the score). It even formed the basis of one of my mini-puzzles that you referred to earlier (funny how all these threads are coming together, isn't it?) The Endorian Forest is, as far as I can tell, the only MM cavern where Willy has to use a crumbly platform to ascend the cavern and then use the same crumbly platform to descend back down again*. That's the scenario in which the efficiency which DigitalDuck discovered was to be found. So perhaps it is a one-off? (*I'm not including cases where Willy descends down through an empty gap where a crumbly platform used to be; in this case the fall would be fatal if Willy dropped through it without partially crumbled platforms to stagger his fall.) *** Anyway, it's nice to know that humans (or even ducks!?) can still outwit computers in this Age of AI...

I've only analysed The Endorian Forest today. I guess other rooms where Willy has to progress downwards by waiting for crumblies to disappear might yield further results? I did wonder why, in both DD and Crem's AI recordings, Willy walked out an extra step (than seemed the bare minimum) onto the crumbly platforms on the way down near the end of Endorian Forest. But then I remembered how you have to step back a bit from a fire cell before trying to jump over it. So there's no further efficiency to be found there, due to the spiky leaf fire cell near the bottom just to the right of the trunk. (In fact, attempting a quick testing out of that manoeuvre (based on a snapshot in QAOPs that I pulled up for convenience, which happened to be from Norman Sword's Manic Jet Set Willy) is what led me to discover the slight difference between the MJSW and MM game engines, as I reported elsewhere.)

Surely the room should be called The Bassment? 😉

I've just noticed something slightly different about the behaviour of the game mechanics in MJSW compared with original MM/JSW. I noticed it in The Endorian Forest, whilst trying to jump leftwards off the bottom right crumbly platform. If Will stands on the far left of that crumbly platform (in such a position that one step leftwards would cause him to stand on the spiky branch fire cell to the left of the crumbly, killing him), and then does a leftwards jump: - In original MM, he hits the Fire cell and dies (because in the first increment of a sideways jump, he moves leftwards and is drawn at the same height; the jumping indicator is set in that pass through the Move Willy routine, but he isn't actually moved upwards until the next time frame; - In MJSW, the movement is the same and he is drawn in the next iteration apparently standing on the Fire cell (although his pixels only occupy the righthand of the two character columns that he occupies in that frame of animation), but he survives the encounter and subsequently jumps over the fire cell and onto the platform above.

Digital Duck took advantage of Willy's ability, when jumping up and landing on a platform above that which he jumped off, to perform a turnaround and vertical jump in a single time frame. Crem's AI did those manoeuvres (in order to collect the top right item) in two consecutive time frames (also had to keep the right key pressed at the end of the first jump to advance Willy by one more frame to be able to collect the item using a vertical jump. So whilst the AI was seemingly 'one step ahead' jumping up off the crumbly, that initial gain was negated by having to take two frames to turn around and jump compared to DD's one frame - at that point they're level-pegging. But then DD's extra frame spent on the upper-right crumbly meant that they didn't have to wait as long (one time frame less) to drop through it later. The middle of the three crumbly blocks is the determinant here - DD has things optimised as both left and middle crumbles disappear at exactly the same time, whereas in the AI recording, once the left-hand crumbly block has gone there is still one more pixel-row of the middle crumbly block remaining to delay Willy's drop.

To answer my own question, no the difference occurs on the top right crumbly platform - Willy walks along one more step before jumping rightwards off that platform in Digital Duck's video, compared with Crem's AI-generated walk through in page 6 of this thread. However, they both land in the same place after the jump (in the optimum position to collect the top-right it), because of different left-right keypresses being pressed at the moment of landing (I think?)

I wonder how the AI failed to pick it up? Is it because it involves momentary inaction in the present to make things more efficient in the future? Mind you, that's the sort of things that humans are less likely to come up with (our in-built instinct is to do something), whereas the brute force AI approach of trying every possible iteration of moves (or in this case non-moves) should have detected it?

Actually, I've just added a timestamp in a comment on your YouTube video (8:52), just before when Will jumps onto the crumbly platform which I think is the one you're talking about (the lower one of the right). Is that correct?

Which platform specifically are you talking about? Could you describe it please, or show an image with it circled or something?

My main current obsession is still my bass guitar! I've not done anything major in the JSWMM scene lately but I do pop in here now and again. No doubt the time will come when I devote more time to Willy's universe. Packaging up a series of minim puzzles is certainly one of the things on my to do list. 😊

Interesting idea, Andy!

You could always change its status to 'unlisted'. That way you would have 100 publicly available videos, but the 'temporary' video would be preserved, and you could send a link for it to anyone who requested to see it.

There is another aspect of the code in that vicinity which is worthy of comment. The way that Matthew hid Willy's legs underneath the Swordfish (at #9071-#9076) is not ideal. He just changed the attributes to black-on-black, but that means that they reappear during the colour-cycling when the remaining air in The Final Barrier is counting down. It's better to wipe the pixels of his feet from the screen instead, which would take about 8 or 9 bytes to replace those at #9071-76 (so two or three more bytes are needed to achieve it): LD HL, #40F3 - point HL at the appropriate place in the pixel screen file [with Matthew's original code, HL will be pointing at #58F3 when flow of execution reaches #9071 so L already holds the correct value and therefore this command could be a LD H, #40 to save one byte. But Danny's more efficient method that he described in the post before this might mean that particular efficiency isn't available, and you might have to define both H and L] LD DE, #???? - point DE at somewhere in the code with 32 contiguous zero bytes CALL #8FF4 That also wipes the pixels from the character row below the one with Willy's 'ghost legs' (that part of the screen should be empty anyway so it's pointless-but-harmless). **** For two more bytes, you can only wipe one character row of pixels (the one with Willy's legs in it), meaning that you would only have to find 16 contiguous zero bytes to point DE at. To do that, replace the CALL #8FF4 with: LD B, #08 CALL #8FF6 - note the late entry point into the 'Draw a Sprite' routine, to ensure that only 1x2 character spaces are wiped, instead of 2x2 as usual

At #904C, H already holds the value #40, so the three-byte LD HL, #40B3 can be replaced with a two-byte LD L, #B3 (I suspect that might be the one that @jetsetdanny already came up with?)

Of course, if we know that C=0 throughout, then those two two-byte commands LD (HL), #00 at #9072 and #9074 can each be replaced by a single byte LD (HL), C. (Unless that's the optimisation which Danny already identified, as he referred to in the third post of this thread?)

XOR C doesn't change the value in C, it only changes the value of A. (And the Flag register - as you say, it resets the Carry Flag.)

Dr Andrew Broad, in his 2008 Remix of Manic Miner, forced the player to visit that spot in The Bank in order to collect (from below) the top-right item, and also made the cavern more challenging overall, simply by removing the trellis structure from the right-hand side of the cavern. Thus forcing Willy to navigate the cavern the hard way. Ingenious! (Although he could have added even more difficulty by moving the portal one character row higher, as that would have forced the player to jump onto the crumbly block, perilously close to the adjacent 'spider' Fire cell, in order to reach the portal - as things stand, Willy can just jump up into the portal from the mid-level water platform that is located below the platform that the portal rests on).