We're (team of 2) rewriting an old enterprise ERP system made of ~1M of C89 non-portable loc, tens of thousands of handwritten PLSQL loc, thousands of business rules carefully abstracted in sql data, tens of complex screen designed and scripted on a no-name RAD software that was the current fad back in the days, and some companion pieces in VB6 because, you known, 'C89, not anybody can do it'.
That's fun.
The new system is a quiet simple SOA arch with a dull, only-real data db layer, backend in Go with code-generation, frontend in es6 migrating to elm.
That looks the IT guys have when we say 'no really, we don't need IIS or Java', its priceless :)
The interesting part actually lies in handling both product management and sales for the new version while handling the day-to-day coding part.
Sometimes I think I should write a book on those subjects :)