Then your screen will always either be blurry

To be fair, how much or little you'd notice the blurriness greatly depends on the kinds of graphics.  Zooming a hi-res photograph in non-integer zoom for example may not be so bad.  Lemmings is a little more unique in that its graphic design is decidedly not anywhere remotely photographic/photorealistic, it is in fact a specifically low-resolution pixelated design, and those are often challenging to do well with non-integer zooms.

Perhaps using the hi-res version of graphics may make non-integer zooms more acceptable?

WillLem's experience with trying a lower display resolution may be partly Window's fault.  At the lower resolution the default DPI is probably left at 1 instead of the 1.5 used for the native HD resolution.  So less applications are being zoomed by Windows for the DPI thing, and at the same time everything onscreen are all zoomed by the hardware to go from 1366 to the native HD.  Perhaps the hardware is doing a better job than Windows, plus with everything zoomed maybe you'd notice blurriness less (compared to the Windows DPI thing, where it may be more noticeable since the selected onscreen stuff that don't need zooming, like the native Windows UI elements, are crisp by comparison to the rest that are zoomed by Windows).

With a simple application of forum search, below thread seems to have the most context on why many decorative objects were changed to moving backgrounds.

https://www.lemmingsforums.net/index.php?topic=3540

In essence, you have Simon and Nepster to blame for this.

From the Quick Guide to Using NeoLemmix Features in the Editor posted by namida circa 2015:

Moving Background

A moving background object is exactly what it says on the tin - a background animation that moves. It will wrap around the level if it reaches the edge. The editor doesn't always correctly draw them behind other objects / terrain, but the game itself always will, regardless of index order or no overwrite settings (however, these settings do still affect how moving background objects are drawn in relation to other moving background objects).

The S Value and L Value are used to set the direction and speed of movement respectively. An S value of 0 represents straight upwards, with each increase of one corresponding to a 22.5 degree (clockwise) increment - so 4 is to the right, 6 is to the bottom-right, etc. The L value is how many pixels it should move per game-time second (which is equal to 17 frames). There is also a quick select panel for these.

Do note that non-multiple-of-45 degree angles (ie: those with odd S values) tend to act like the closest non-diagonal line if the speeds are very slow. Also, do note that the formulas are not always 100% reliable due to rounding, so you may need some trial-and-error if for some reason you want a moving background object's position to be overly precise.

The only default graphic set that contains these is the Space graphic set from Lemmings Plus IV. Some custom graphic sets (such as the Honeycomb set from Lemmings Plus V) also contain these.

It seems like always forcing no overwrite wrt terrain is by design, since these kinds of objects are meant to be part of the background in essence.  So the real question/mystery is, like namida said, why so many no-effect objects were reclassified?  It also sounds like respecting only-on-terrain was unintentional for this kind of object.

Quote from: IchoTolot on June 08, 2020, 02:58:45 PM

I would even propose legacy to be the stadard option as it's close to the DOS version and likely familiar to new players. Also all current custom pack menus are running with it and it is ensure the pack layouts are working.

This could potentially be misleading to new players expecting NeoLemmix to be like DOS: we've already observed that it has this effect. This is one of the many reasons I think NeoLemmix's menu needs an update.

NeoLemmix borrows too much graphics- and sound-wise currently to break the close association with DOS Lemmings.  I don't think merely changing the menus would make people assume otherwise.  And honestly, even if it uses all new graphics and sound, you're still bound to get some people saying that, for example, they'd want bombers to be timed like DOS Lemmings.  At the end of the day it's a lemmings-like game, and some people especially new players will naturally expect or prefer certain behavioral details to match the actual Lemmings games, even when the NeoLemmix community purposely moved away from those same things.

So, here are my comments for Original, which happen to be concerning the Mayhem levels.

Removing bombers from Mayhem 4 seems reasonable.  I'm less convinced about Mayhem 26, challenge solutions are expected to involve moves every now and then that are pixel- and/or timing-precise.  The change could make sense for something like Redux, but seems unnecessary to me for a version of level specifically for challenge purposes.

One other reason is - some people have expressed interest in trying to do this anyway; one even trying to figure out a workaround to emulate this with features that do exist (it's possible - but I'm not going to explain how, and I don't believe that person figured it out).

Any chance it can be shared out (even if vaguely) what kind of triggered animation they want to do?

Whatever animates and is not recognisable as some other gadget is a trap.

Doesn't NeoLemmix still have constantly animated decorative objects?  Or is that also removed?  It feels like your argument would also apply to any decorative objects, not just ones that need triggering.

I could maybe see some use of a triggered decorative animation that only happens once.  I'm more skeptical of infinitely triggerable decorative animation, that might simply get too distracting for some people.  Would be interested to see how exactly they had been used in the past before getting culled.

I noticed that many styles don't carry all the different object types.  It's entirely possible for a new player to not recognize some objects because the levels they played so far never featured a particular kind of object.  I'm less convinced than Proxima that all the non-trap object types are all easily recognized by many.

Sound could perhaps be a way to convey danger even when the player isn't actively looking at a triggered trap.  Decorative triggered animations should either have no sound or a sound that doesn't convey danger, to contrast with triggered traps with more disturbing sounds.

At the end though, it does seem a little hard to not get potentially someone to wonder, did something actually changed in the level even though I can't seem to see any changes.  After all, it certainly looks like the object have responded to the lemming passing by, doesn't that kind of mean something of significance must have happened?  Constantly animated decorations at least don't behave like they are responding to lemmings passing through, so it seems much less likely for people to get confused about lack of changes to lemmings and level.  (Although that said, I still think it's preferred to keep such decorations out of direct way of lemmings at least for the most likely solution paths.)