Rustual Boy is a Virtual Boy emulator. It can be used to play existing Virtual Boy games, as well as be a helpful development/debugging tool for homebrew for this platform.
The name "Rustual Boy" is a portmanteau of the words Rust and Virtual Boy. Ok, the Virtual Boy part was obvious, but why Rust? In fact, Rustual Boy is written in the Rust programming language - a "systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety." Rust is a wonderful language with a thriving community, and as such provides a fantastic platform for an emulation project!
Rustual Boy is currently able to emulate the majority of commercial Virtual Boy titles, as well as many homebrew ones. It supports basic video/audio output and keyboard input, and also a simple CLI debugger. It runs on Windows, MacOS, and Linux.
While Rustual Boy's core emulation is nearly complete compatibility-wise, and in some respects is already one of the more accurate VB emulators available, the project is still young, and needs some time to mature. Particularly, its user interface is lacking (read: virtually non-existent), there are some known (and probably unknown) stability/compatibility issues, and performance isn't fantastic yet, but the emulator should be playable at least.