Indeed, it is super complex. It's been much harder than we initially expected. We'd thought maybe two years--it wouldn't be fast, but it would be complete. But things like invokedynamic instruction, annotations, etc. have added complexity far beyond what we originally expected. But it's been highly instructive. And it's great fun to see full Java programs execute and watch the instructions fly by as they execute. On average we're presently at about 1/3 the performance of the JDK with the -Xint (interpreter mode) flag set. (Some of that performance penalty is due to using go vs. HotSpot's use of C.) We hope in a year to be able to invite interested folks to try it out with their code.