Rux's goal is to become a safe general-purpose microkernel. It tries to take advantage of Rust's memory model - ownership and lifetime. While the kernel will be small, unsafe code should be kept minimal. This makes updating functionalities of the kernel hassle-free.
Rux uses a design that is similar to seL4. While there won't be formal verification in the short term, it tries to address some design issues of seL4, for example, capability allocation.
The code is very approachable for anyone interested in capability-based microkernel design.