macOS ships moving wallpapers, but only its own

That is a narrower position than Android's and a wider one than the iPhone's. Apple gives you motion, and gives you good motion, on the strict condition that it is Apple's. Everything here follows from that division.

What Apple's own moving desktops are, and where they stop

Apple's own moving desktops come in two forms, and telling them apart saves a lot of confusion. Aerial wallpapers are slow video sequences, mostly landscape and city footage, which play when you wake the Mac and then settle onto a still frame rather than looping forever. Dynamic desktops are still images that change through the day, shifting between light, day and dark versions in step with the clock, so they move over hours rather than seconds.

Both are closed sets. You choose from what Apple supplies, and there is no supported way to add your own aerial to the list or to build your own dynamic desktop from your own images through the system's own settings. That is the reason every product that sells a live wallpaper for Mac exists.

Why your Mac wallpaper is not moving

A Mac wallpaper is usually not moving for one of five reasons, and four of them are not faults.

1. Confirm you picked an aerial or a dynamic desktop rather than a still, since most of the supplied backgrounds do not move at all.
2. Wait for the download to finish, because an aerial has to fetch its video before it can play and shows a still frame until it does.
3. Expect an aerial to play on wake and then hold, which is the designed behavior and not a failure.
4. Check Low Power Mode and the battery settings, since macOS trims optional work of exactly this kind when it is conserving power.
5. Check that your third party wallpaper program is actually running and has been granted the permissions it asked for at install.

Wallpaper Engine does not run on a Mac

Wallpaper Engine is a Steam program that plays video and scene wallpapers, and it is Windows only. There is no macOS build and none has been announced, which is the single most common disappointment among people arriving at this subject from a PC. It runs on Linux and on the Steam Deck through Proton, unofficially and without support, and there is a separate Wallpaper Engine for Android that imports wallpapers from the desktop version. There is no iOS version either. A Mac needs a different program entirely, and the free open source ScreenPlay is cross platform, which makes it the closest equivalent that will actually install.

What a third party moving wallpaper on macOS actually does

A live wallpaper is a video your device never stops playing, and on macOS a third party tool achieves that by drawing a full screen window behind your icons, which is a workaround rather than a system feature. That shows in three ways. The program must run for the wallpaper to exist, so it launches at login. It usually needs a permission grant to draw where it wants. And it does not inherit the behavior of the built in wallpaper, so anything you relied on from Apple's version has to be reimplemented by whoever wrote the tool.

One system behavior does carry over and is worth planning around: macOS sets a wallpaper per display and does not span a single picture across two of them, which is the opposite of Windows and its Span option. A two monitor Mac needs two files, or two copies of the loop, one sized to each panel.

The dimensions a Mac desktop actually needs

Read the pixels column and ignore the points column, because macOS reports points and the panel has pixels, and on a Retina display there are two pixels per point in each direction. A file built to the reported number therefore arrives at half resolution and is upscaled, and that is the single commonest cause of a blurry Mac wallpaper. It is also why a 4K live wallpaper is not automatically enough here: 3840 x 2160 is short of a Studio Display at 5120 x 2880 and short of a 24 inch iMac at 4480 x 2520, and none of the MacBook panels is 16:9 in the first place, so a 4K loop gets cropped as well as scaled.

The cropping is worth stating exactly. macOS scales a desktop picture to fill, cutting whichever axis is proportionally longer, unless you pick Fit To Screen or Stretch in the wallpaper settings. Fit To Screen keeps the whole picture and leaves a border. Stretch keeps neither the shape nor the picture. Fill is the default and it is why the edges of your image disappear. The same picture is a different file on every Mac in that table, and the differences are not small.

What a moving desktop costs a MacBook on battery

A moving desktop on a MacBook draws power whenever the desktop is visible and nothing at all when the screen is off or a window is in front of it, which is the same rule that governs every platform. What differs on a Mac is a detail people get wrong: a black wallpaper does not save power on a backlit laptop panel, because the backlight is on regardless of what is in front of it. Switching a subpixel off to save power is an OLED property, and it is why black backgrounds are a genuine battery recommendation on an AMOLED phone and a purely aesthetic choice on a MacBook.

If you want the effect without the running cost, a dynamic desktop is the middle option Apple already supplies: it changes across the day, costs a still image to display, and never renders a frame you did not ask for. Finding the picture is the easy part of a Mac wallpaper. Keeping it sharp at the panel's real pixel count, and being sure it is yours to use, is the rest of it.

Where to go next

DEVICESYour desktop, your phone and your tablet each want a different wallpaper fileWallpaper sizes by deviceWALLPAPER ENGINEWallpaper Engine is a Steam program that plays things on your desktopWallpaper Engine, explainedLIVE WALLPAPERA live wallpaper is a video your device never stops playingWhat it is and what it costs