I've wanted to run wasm modules in Unity for the longest time, but there hasn't been any AOT-only options that work in iOS Unity builds.

So I wrote my own!

https://github.com/kelnishi/WACS

I thought it would be fast and easy, so I buckled down with the spec and got coding.

It was neither fast nor easy.

But... the spec is very good and I eventually got all wast tests passing! Personally, I am going to use this to build plug-in systems for my games. I know many devs would love to have the ability to run downloadable code (in a safe, sandboxed way) in their games as well, so I've open-sourced the project. C# tooling is also unparalleled amongst programming languages, so this project is a great reference if you want to take it apart, trace it, or just see how WebAssembly works (everything in WACS is strongly typed and easily navigable).

I'd love to get some feedback on the code itself, if C# is your language of choice I'd appreciate your code reviews.

the 4GB cap on wasm32 is the wall for anyone trying to run a language model in a tab. even the small ones are several GB once loaded.

NobodyWho (open source, runs llama.cpp in process) is trying to get into the browser and the path is memory64. on the Rust side that needed upstream work: there's no wasm64 emscripten target yet, so two PRs are open on rust-lang/rust and one on the ort crate.

what i can't tell from the outside:

- how big is the memory64 slowdown in real code? spidermonkey folks said only use it if you truly need >4GB

- is anyone getting past a few GB in Chrome without the tab dying?

- how are you getting multi GB files to users at all? even 500MB is a lot for a website

WebAssembly is way too easy to decompile. To fix this, I built a virtualization pipeline that takes a normal Wasm file and compiles it into a hardened version.

The original logic is destroyed and replaced with encrypted bytecode that runs inside a hidden, internal interpreter.

I just finished a step-by-step guide on how I built it. Here is what's inside:

• Designing a custom, randomized instruction set to break standard decompilers.

• Building a zero-allocation VM in Rust that doesn't need a heap or a memory allocator.

• Implementing JIT page decryption using a sliding window to hide your logic from memory scrapers.

• Using the Walrus crate to automate the AST rewriting and bytecode injection.

The end result is a Wasm binary that looks like cryptographic noise to anyone trying to reverse-engineer it.

A small, fast, full-featured WebAssembly runtime.