You put both Rust and Nim at 'Medium complexity to learn' but given that by default Rust has the 'borrow/lifetime checker' and that Nim has the GC, I'd say that Nim is easier to learn/use. Of course you pay the price in performance (GC latency), even if Nim's GC is described as 'soft real time' I doubt that it would work well for a >60fps game and now with VR if the framerate drop you can make the user dizzy..