In addition to Mike Acton's talk, there is also the "DOD Book": https://www.dataorienteddesign.com/dodbook/

For me, this is Odin-Lang, it doesn't meet all the requirements you have listed, but it's ergonomic, fast, and comes with extensive core and vendor libraries. It's all just fun and reasonable.

https://odin-lang.org/

Oh, that's quite on the mark!

Nitpicking: I'm not fond of reserving keywords like len or append.

  len(arr)
  append(arr, v)

Better is

  arr.len
  arr.append(v)

Also

  x: [dynamic]int

is quite verbose

Maybe better would be

  x: [int]   //dyn
  x: [int,2] //fixed

Disappointing that it hasn't launched with linux support per the original RAD debugger announcement, but to my understanding the project has been restarted several times since then.

It's still in alpha so not that big a deal. Vast majority of users will be on Windows, so perfect for identifying bugs quickly, and then Linux should hopefully get a stable port soon. Personally code primarily on Windows but a good GUI debugger would make me very seriously consider Linux as an option to get finally get away from Microsoft