Author Topic: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini  (Read 3486 times)

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Offline Ron_Stard

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I've attached here replays of what I consider several "bugs" (?) I've encountered while playing some levels in SuperLemmini:

Lemming trapped in "Scaling the heights" (Oh No! More Lemmings!)
Climber that crosses through bridge in "Have a nice day" (Sega Genesis Lemmings, but probably also in Original Lemmings)
Blocker that doesn't block on (descending to the left) steep path in "Valley Of Fire" (Van Clan Lemmings)
Builder that doesn't build at the very (left) edge on "Up, Down or Round and Round" (it's possible to build a bridge one step beyond when facing right, as seen on the replay)
-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini. I don't know if this trick works on Amiga, but since Mazulems was composed in the late MS-DOS days, I assume that it will work on MS-DOS.
-Hail 6 ("Surprise Package?") it's very hard to solve with the % required. On Amiga and/or DOS, it's fairly easy even to surpass the objective.

What do you think about these... "bugs"?
« Last Edit: April 28, 2020, 09:35:10 PM by Ron_Stard »

Offline WillLem

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #1 on: April 21, 2020, 03:12:22 PM »
Thanks for reporting these Ron_Stard. My best guesses for each:

Lemming trapped in "Scaling the heights" (Oh No! More Lemmings!)

This one's quite a common glitch that happens in a lot of early versions of Lemmings. Assigning a Climber to a stuck lemming can free them, as can using a destructive skill, of course.

I'm not sure this one's a bug - I'm guessing Tsyu has purposely left this in as a glitch as it's part of Amiga physics, and I'm fairly sure that SuperLemmini models Amiga physics quite closely. I could be wrong about this, though.

Climber that crosses through bridge in "Have a nice day"

If the builder bridge is started on the very edge such that the pixels only just overlap, Climbers are able to climb through it. Again, this is something that happens in Amiga Lemmings as well. See this video of my playthrough of Postcard From Lemmingland - I cancelled the attempt due to this happening (link is at the correct point in the video).

Again, this is possibly something that has been left in purposefully (but maybe not).

Blocker that doesn't block on (descending to the left) steep path in "Valley Of Fire"

This one's definitely not a bug. Blockers have two trigger areas (one for each hand), with a gap in between where the Blocker's body is:



The example you've given is quite normal, and happens particularly on steep slopes when one of the Blocker's trigger areas is past the edge of the sloping terrain: the lemmings can walk over and through the Blocker the same as when they fall through a Blocker from directly above:


Note that the Blocker's right-side trigger is past the edge of the terrain, and so will have no effect on the lemming walking down the slops. The left trigger, however, connects with the slope and so will stop lemmings walking up the slope.

Builder that doesn't build at the very (left) edge on "Up, Down or Round and Round" (it's possible to build a bridge one step beyond when facing right, as seen on the replay)

After testing, I can confirm that this happens on the Amiga as well, and also in WinLemm: left-facing builders overlap an edge by at least 2px, whereas right-facing builders can overlap by just 1px.

It'll depend on whether or not Tsyu has purposefully left the first two in as faithful recreations of Amiga physics as to whether or not these things get fixed, and the third is, in fact, standard Lemmings physics.

Hope this helps.
« Last Edit: April 21, 2020, 08:41:16 PM by WillLem »

Offline Ron_Stard

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #2 on: April 21, 2020, 05:14:46 PM »
Thank you for your responses, WillLem. I don't know very well if Amiga physics are the same as MS-DOS and Lemmix/Vanilla Lemmix (by Vanilla I suppose people refer to EricLang Lemmix). I have to play these Lemmings levels in Amiga and also in MS-DOS in order to confirm the "bugs". But as I mentioned, they seem strange to me.

By the way, when you talk about WinLemm, you mean Lemmings 95 or WinLems?

[ Link for the second one: https://github.com/warrengalyen/WinLems ]
« Last Edit: April 21, 2020, 05:44:45 PM by Ron_Stard »

Offline WillLem

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #3 on: April 21, 2020, 08:34:21 PM »
Builder that doesn't build at the very (left) edge on "Up, Down or Round and Round" (it's possible to build a bridge one step beyond when facing right, as seen on the replay)

After testing, I can confirm that this happens on the Amiga as well (and also in WinLemm, and in DOS according to namida): left-facing builders overlap an edge by at least 2px, whereas right-facing builders can overlap by just 1px.

By the way, when you talk about WinLemm, you mean Lemmings 95

Yeah, Lemmings 95 for Windows; the version whence SuperLemmini extracts its graphics.
« Last Edit: April 22, 2020, 12:03:42 AM by WillLem »

Offline Ron_Stard

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #4 on: April 28, 2020, 09:34:57 PM »
Thank you for your research, WillLem!

I think I've found [another] two "bugs" (?):

-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini. I don't know if this trick works on Amiga, but since Mazulems was composed in the late MS-DOS days, I assume that it will work on MS-DOS.
-Hail 6 ("Surprise Package?") it's very hard to solve with the % required. On Amiga and/or DOS, it's fairly easy even to surpass the objective.

Offline Proxima

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #5 on: April 28, 2020, 09:42:02 PM »
-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini.

Absence of a bug isn't a bug :P

Offline Ron_Stard

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #6 on: April 28, 2020, 09:51:47 PM »
-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini.

Absence of a bug isn't a bug :P

Haha, good point! But was it really a bug, or an intended behaviour?

Offline namida

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #7 on: April 28, 2020, 09:53:29 PM »
Quote
-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini. I don't know if this trick works on Amiga, but since Mazulems was composed in the late MS-DOS days, I assume that it will work on MS-DOS.

To the best of my knowledge, this trick does work on Amiga. It definitely does work on DOS. However, it's important to keep in mind that SuperLemmini doesn't claim to exactly reproduce Amiga physics, just to be "based on" them.

Quote
-Hail 6 ("Surprise Package?") it's very hard to solve with the % required. On Amiga and/or DOS, it's fairly easy even to surpass the objective.

I suspect this may be that to accomodate SL's double resolution while keeping a similar feel, it also doubles the frame rate - but keeps "one lemming starts counting down per frames". If SL actually wants to keep the original feel here, it should be "start a countdown once every two frames". However, this isn't really a "bug", just a physics difference that Tsyu may or may not want to adjust. Probably not a bad idea to adjust the level a bit (perhaps by doubling the lemming count?) to accomodate if he decides not to change the physics, though.

Offline WillLem

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #8 on: April 28, 2020, 10:33:10 PM »
Has anyone heard from Tsyu recently?

Offline Tsyu

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #9 on: June 13, 2020, 06:56:09 AM »
Lemming trapped in "Scaling the heights" (Oh No! More Lemmings!)
I'll investigate this a bit further, but I think this can happen in the Amiga version. Basically, the game checks only a few pixels (one pixel at the feet and two at the head in the original game) to determine whether the builder has hit a wall or ceiling, and if the builder is deep enough in the ground (seven pixels in the original game) when it stops building, it will get stuck.

Climber that crosses through bridge in "Have a nice day" (Sega Genesis Lemmings, but probably also in Original Lemmings)
As WillLem showed, this can happen in the Amiga version too.

Blocker that doesn't block on (descending to the left) steep path in "Valley Of Fire" (Van Clan Lemmings)
WillLem explained this well.

Builder that doesn't build at the very (left) edge on "Up, Down or Round and Round" (it's possible to build a bridge one step beyond when facing right, as seen on the replay)
Yeah, the brick positions for left- and right-facing builders aren't symmetrical, even in the original games. (I will still try this level in the Amiga version to see whether that also requires two builders for that gap.)

-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini. I don't know if this trick works on Amiga, but since Mazulems was composed in the late MS-DOS days, I assume that it will work on MS-DOS.
You mean what the climber does here?

https://youtu.be/D6Ren_bMVcU?list=PL16FA900A49F71C61&t=67

What's happening here is the climber moves away from the wall by at least a pixel when it hits a ceiling, which I'm pretty sure happens only in some versions of the game and not the Amiga version. (I will still check it, just in case.)

-Hail 6 ("Surprise Package?") it's very hard to solve with the % required. On Amiga and/or DOS, it's fairly easy even to surpass the objective.
Yes, I just verified that the level is indeed difficult in SuperLemmini. I need to investigate this further. (And the game does nuke each lemming every two frames as it should [I just verified this], so that's not the problem.)

Offline Ron_Stard

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #10 on: June 13, 2020, 12:55:08 PM »

You mean what the climber does here?

https://youtu.be/D6Ren_bMVcU?list=PL16FA900A49F71C61&t=67

What's happening here is the climber moves away from the wall by at least a pixel when it hits a ceiling, which I'm pretty sure happens only in some versions of the game and not the Amiga version. (I will still check it, just in case.)


Yes, that trick. namida mentioned this also happens in Amiga. However, I didn't test it yet. An obvious and quick way to verify this is playing Amiga Fun 11 in an emulator, and see if this trick works in both walls of the level. I can check it later.
« Last Edit: June 15, 2020, 01:21:11 PM by Ron_Stard »

Offline ericderkovits

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #11 on: June 13, 2020, 01:10:21 PM »
hi Tysu finally heard something from you. How's the update on Superlemmini going? Me and WillLem finally were talking about you.

Offline Ron_Stard

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #12 on: June 15, 2020, 04:10:58 PM »

You mean what the climber does here?

https://youtu.be/D6Ren_bMVcU?list=PL16FA900A49F71C61&t=67

What's happening here is the climber moves away from the wall by at least a pixel when it hits a ceiling, which I'm pretty sure happens only in some versions of the game and not the Amiga version. (I will still check it, just in case.)


Yes, that trick. namida mentioned this also happens in Amiga. However, I didn't test it yet. An obvious and quick way to verify this is playing Amiga Fun 11 in an emulator, and see if this trick works in both walls of the level. I can check it later.

I tested it on that level and yes, that trick works on both directions.

Offline Tsyu

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #13 on: June 19, 2020, 08:52:12 AM »
I said that I would investigate some of these bugs, so I did. Here's what I found:

Lemming trapped in "Scaling the heights" (Oh No! More Lemmings!)
I checked the Amiga version, and I couldn't get the lemming stuck there. This probably is a consequence of the higher resolution.

I don't know how to solve this without making something else harder or even impossible. For instance, changing the builder's upper collision check to be one pixel further out may fix this, while making it harder to build up to a wall without leaving a gap.

-In Mazulems 16 ("It's a Magical World"), the "magic trick" no longer works on SuperLemmini. I don't know if this trick works on Amiga, but since Mazulems was composed in the late MS-DOS days, I assume that it will work on MS-DOS.
I just checked the Amiga version: The lemming does indeed move away from the wall by an extra pixel upon reaching a ceiling. I've changed SuperLemmini to do the same (albeit by two pixels to account for the higher resolution).

-Hail 6 ("Surprise Package?") it's very hard to solve with the % required. On Amiga and/or DOS, it's fairly easy even to surpass the objective.
It looks like the level is just as "hard" in the Amiga version, if not just a tiny bit easier. I think the speed at which the release rate is increased, as well as when the nuke is timed, affects how many lemmings you will save. (Using the one blocker to better consolidate the crowd can also help.)

However, in the DOS version, I typically save many more lemmings (at least 10% more), and I know why. As you know, if a bomber's timer runs out while the bomber is on the ground, it will enter an "oh-no" state before exploding. What's interesting is what happens if the timer lapses while the lemming is exiting, which (as you might expect) is fairly common in this level. In the Amiga version (and in SuperLemmini), the lemming will enter the "oh no" state and then explode, without trying to exit the level again. In the DOS version, however, the lemming enters the "oh no" state for one frame and then exits the level, doing so successfully. This explains why the level is so much easier in the DOS version.

(I also found that SuperLemmini's bomber timer was a few frames too short, so I fixed it. This doesn't actually affect the difficulty of this level, though, because once the first lemming's timer lapses, the others' will lapse one by one every two frames, just as before.)

Offline Proxima

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Re: [BUGS] Several bugs in Lemmings behaviour within SuperLemmini
« Reply #14 on: June 19, 2020, 11:55:55 AM »
I just checked the Amiga version: The lemming does indeed move away from the wall by an extra pixel upon reaching a ceiling. I've changed SuperLemmini to do the same (albeit by two pixels to account for the higher resolution).

Your choice, of course, but I don't agree that imitating a bug in the original games is the right decision, even if there is a custom level that exploits the bug. Levels can be edited, but a bug in the climber mechanics potentially affects every level using climbers. (And as the NeoLemmix version proves, in this particular case the level is solvable without relying on the bug.)