Light Onion Router is a project I developed in 2015-2016 because I needed to make a hidden service reachable without using Tor (this is kind of strange, I know). The main purpose, in fact, was to create a malware capable of connecting to its C&C completely via the Tor network.
Well, Tor binary's size is a few megabytes, while this little adapter's size is about 500KB (maybe less with correct optimizations). Also this comes as a library to be embedded in your project, so your software does not need to make SOCKS connections to the Tor binary.
That was the funniest and hardest part to me. I first realized a version using OpenSSL, but the output was very big, then I decided to switch entirely on mbed TLS.
This is a proof-of-concept and should NEVER be used in production environments. It was fast coded and has not proper data structures and code design to handle serious problems (no event loop for example). It was just made to demonstrate that malware living entirely on Tor, without any kind of proxy or workarounds, can be realized.