Is there a difference between version 2.1.0 an 2.1.1? The only difference I see when quickly looking at contents is the factorio version number in info.json.

To achieve (explicit) compatibility with both 0.17 and 0.18 I think you can set factorio_version to 0.18 (like in 2.1.1) and in your dependencies base >= 0.17.0. This way you don't have to release two version of your mod every time.

Your assessment is correct. 2.1.0 and 2.1.1 are functionally identical, but are released separately for compatibility with both stable and experimental Factorio. It's incredibly clunky, but I don't know how else to do it. I care a lot about my version numbers, so this issue bothers me a lot.

I tried your suggestion just now. Factorio 0.17 loads the mod successfully, but disables it silently, citing incompatibility. Maybe I'm doing it wrong. If you know of a working example of your suggestion, please link it here. Thanks for your help.

Installed 0.17 to test and indeed it doesn't work. Sorry.

I just can't believe that there is no solution for this. It seems like a problem every mod author would run into.