Hello friends,
I have a MacBook and I have both TFM and Steam downloaded. Steam works for me just fine, but TFM doesn't load at all, whether I open it by itself or through Steam. It starts running like it's going to open, but all I get is the app bouncing, the white dot underneath it, and nothing else. I have tried removing and redownloading TFM on Steam but nothing changes. Also, TFM is not showing up under my Applications tab in Finder; I have to search for it to find it, although it does say that it's listed under the App tab. I don't know if that has anything to do with anything, but I thought I'd mention it just in case.
If someone can help me, I would be very appreciative! I tried emailing Atelier directly but I haven't heard a response back in weeks. I haven't played in probably a month and a half to two months, and I miss TFM

I've encountered the same issue, and it also shows the game is running and icon shows up at dock for me. I also tried reinstalling the macOS system and it didn't help at all. I also tried emailing Atelier couple weeks ago and haven't gotten any response. Just hope they could have it fixed soon :(

I have this issue on an Intel Mac running the latest macOS, but two other Intel Macs I'm using with older macOS versions don't exhibit the same behavior. I haven't braved installing Steam and Transformice on a Mac with Apple Silicon yet but would be glad to attempt troubleshooting suggestions on those few Intel-based Macs.

I have the same issue. Has anyone figured anything out? :((

I'm not a Mac user, so I have no clue what's wrong with the Mac Steam client or how to fix it...

You could perhaps try running the game on a standalone Flashplayer; I have explained how to do this here. I don't know if these older Flashplayers still work on a current Mac system. (The Windows and Linux versions are still functional.)

Also, I just found that the Transformice standalone for Mac can still be downloaded, even though there is no link to it on the Transformice homepage. (I saw that the download link for the Windows version is https://www.transformice.com/Transformice.exe, so I just tried https://www.transformice.com/Transformice.dmg on a whim to see if that was perhaps the link to the Mac version, and it was...)
I don't know if it still works, and even so, it will probably require Adobe Air. (Apparently the latest Air version won't work on every system - further down the page it says that some users may need an older one. I wonder if that has anything to do with the problems getting TFM running? Does the Steam version use Air, too?)

BTW, this was written under "known issues" on the Air download page; I have no idea if it's relevant:

Adobe Air a dit :

Launch failure on M1 hardware. Some AIR applications will fail to launch when run on a device using Apple Silicon (M1 / ARM hardware). To work around this, please right-click on the application icon within Finder, choose "Get Info", and on the resulting dialog, select the checkbox "Open using Rosetta".

The .dmg file contains an installer file that won't run on newer versions of macOS.