pak4.pk3 doesn't exist, but pak0-3 does. The pak4 was an error in the readme, but you've come to the right place if you need a better engine for your Steam Q3A. This one's got splitscreen support, native 16:9 resolution UI, & a crap ton of bug fixes against the one provided by Steam. And it's still usable with your Steam copy, all the way down to scorekeeping, etc. The only thing that it doesn't have is compatibility with older Q3 mods, demo replays, & even the master server (!) like the original does, mainly due to unification of the ui.qvm with cgame.qvm. And Spearmint's open source, too.