It's just what it sounds like. Hand written, delicately debugged, well-commented, ARMv7 assembly. Work on this started before ARM64 devices were a thing, so support for them may come in the future. Rather simple, make an app that compiles, runs, and draws something on the screen, using only hand written assembly. The only times I used the assembly output of clang was to determine the proper .sections for things, to let lldb be able to debug my functions.