alt Hacker NewsCrystal has an explicit static type system and is actually optimized at the language level for AOT compilation. These features are pretty much required for compiling and maintaining large programs.
This is for a limited subset of Ruby - almost no popular Ruby gems would run under it. It's more like PreScheme [1] (ie. a subset of a language oriented at C compilation).
I don't think these compete in the same niches right now. Full Ruby almost certainly requires a JIT.
It's a similar subset to mruby, and it might well end up influencing mruby, which does have its users. But it's almost a different language in some ways.