It probably is, and that is just fine. As long as enough of us value being able to use Ruby they'll do ok. Not everything needs to aim to become a unicorn.
Sure you can try out your game immediately in the editor, by pressing the play button - but can you edit Source code and it will be immediately applied without restarting and without losing the current game state?
You can edit and adjust scene objects in the inspector during play mode but those changes are usually thrown away after quitting play mode.
I never did serious mobile dev with unity but I same as above... updating and editing your game source persistently at runtime during playing doesn't seem possible, since it's completely compiling everything into an Android package right?
Building for all desktop platforms under a minute - this is 100% not true..... Almost all of the last hours of game jams where I used unity where spent in worry waiting for a long build process not being sure everything works all right afterwards - and that was always for just _one_ platform at a time...... DragonRuby builds your games into fully functional Windows, Mac, Linux, HTML5 and FWIW Raspberry Pi builds in under a minute in total for all those platforms. I don't know of any other Engine (except maybe LÖVE2D which is interpreted in its basic nature and doesn't need building) which can do anything close to that speed
Persistent flexibly modifiable game state? - maybe there's something in the asset store - but out of the box?
Cross-platform File storage is the only thing where I can see that that is probably a well solved problem in Unity....
I cannot speak for the other game engines. But in general it would be nice if you back up your claims.....
Godot is smaller and has way way less learning material (and no Asset Store), but purely from an Editor perspective it's miles ahead from a dX perspective.
From my experience so far one big point in favor of DragonRuby is that its philosophy focuses on developer productivity, for example
- an iterative immediate feedback style of development using hot reloading
- (in the latest version) direct source code editing and updating via a HTTP Developer interface (think updating your smartphone game at runtime without re-deploying)
- Producing builds for all Desktop platforms in usually less than a minute (mobile and consoles probably take longer considering the surrounding tasks of signing apps, registering in stores etc)
- offering a centralized interface for persistent game state which is automatically dumped for error analysis in case of failure and able to be recorded/replayed/rewinded out of the box during dev
- Abstracting away File Systems/Storage mechanisms out of the box so you don't have to care about where you save on a Switch, PC or iPhone
and probably lots of other stuff I'm not quite aware of atm.
Another big plus point is the lively and encouraging Discord community