I don't want to make a new topic for every little thing I want to suggest, so I'll just start posting comments in this one :)
This file has a list of mruby limitations https://github.com/mruby/mruby/blob/master/doc/limitations.md
The currently used mruby version is 1.9 https://twitter.com/icculus/status/1119557536804483072
Right?! This was a last-minute "I need animation to demonstrate that this goes into a render target" and it's awful. The original looked like this, but uh, copyrights:
I'll make that suck less when I get a moment.