As it stands, we already have a high-performance, sandboxed VM that we are maintaining successfully, and our editor environment is decidedly _not_ multilingual for historical reasons/lack of investment. It'd be very, very expensive for us to see any of the advantages of wasm for the platform today, and it wouldn't really do anything about our existing need to support the millions of lines of code written in Luau today.

Also strategically, wasm is a massive project coordinated by a large number of companies, and it doesn't seem especially prudent to bet the success of a single multibillion dollar company and their entire platform on a project that they don't control the destiny of.

Agreed. I think an underappreciated aspect of choosing a script VM in the space Roblox is in (user-generated content where scripts are content) your product is at the mercy of whoever controls your scripting implementation.

The scripting engine is an integral part of your product, and you need to "own" it end-to-end. Any bugs that creep into new versions of your scripting engine, any API breakage or design changes that impact your usecase are things that you are responsible for. Roblox owns the entire toolchain for Luau, and it's relatively small compared to the set of libraries required to compile to and execute WASM in a performant way.

The nuances of your typical JITing WASM runtime or V8 are pretty hard to learn compared to a simpler VM like Luau, it's a big reason why I've used Luau in my own projects.

how sandboxed is Luau really?

enough that we run a multibillion dollar business entirely off of executing untrusted code on our hardware

LunarEngine is built on raylib, which compiles to WASM. FWIU it might be possible to compile a Luau game to WASM with LunarEngine eventually.

"LunarEngine: An open source, Roblox-compatible game engine" (2025) https://news.ycombinator.com/item?id=44995147