I finally got a chance to install Steam + CRUMB on my old Windows (10) laptop, and the Save function works exactly as you'd expect it to, it pops open a Save dialog box. Clicking "Open" pops open a similar box, too. So at this point, I'm unsure what else to try on my Macbook. I don't really use this Windows laptop anymore (it was only luck that I still had it around), I'd much rather have it working on my Macbook. If you have any suggestions, I'd be happy to try. If I can find the time tomorrow or Thursday, I may try uninstalling Steam and deleting the related game directories, and then re-installing just Steam and CRUMB and seeing if anything changes.

In Security & Privacy > Privacy > Files and Folders, Crumb is not explicitly listed (Steam is, but none of the Steam games), and there's no way to add an app; the only apps listed are the ones where it popped up a "Allow this app access to ____" dialogue box in the past. Steam did request access when I first installed it, but none of the apps in Steam ever have. I *did* go into the Security & Privacy > Privacy > Full Disk Access, and there's the ability to add apps not listed. I added both CRUMB and Steam. That did not fix the problem though. If I can get a chance, I'll try to dig an old Windows laptop out of storage and install CRUMB to test the save function and make sure it's not a misunderstanding on my part.

I double-checked that Rosetta is installed: gzurko@L-GZurko Contents % lsbom -f /Library/Apple/System/Library/Receipts/com.apple.pkg.RosettaUpdateAuto.bom ./Library/Apple/usr/lib/libRosettaAot.dylib 100755 0/0 334960 4072993205 ./Library/Apple/usr/libexec/oah/libRosettaRuntime 100755 0/0 381680 4027196121 ./Library/Apple/usr/share/rosetta/rosetta 100644 0/0 64 1875722922 When I right-click on the CRUMB app in Finder, and click on "Get Info", I don't see an "Open using Rosetta" check-box anywhere, per these instructions: https://www.macworld.com/article/338843/how-to-force-a-native-m1-mac-app-to-run-as-an-intel-app-instead.html Here's what I get: I also do not see this option when checking the info for the Steam app itself. If there's some other way to force it to run with Rosetta, I'll be happy to try it. >>I will take a proper look in the morning? Of course, take your time! I'm still having fun playing with the included demos. I had just built a simple 555 clock circuit and wanted to save it. No big loss of time. >>Could you just check that build number again for me? That’s not the one that is live? Do you mean 10107518? I double-checked, and it's 10107519, unless there's somewhere else I should be looking. In Steam, I right-click on Crumb and choose Properties > Updates, I get: