That "a" stands for "not quite ready yet". This is sort of an intermediate release that focuses mainly on online multiplayer, which is largely functional, but needs more testing. Aside from polish and bug fixes, the only other things I'm going to add are more weapons and special abilities. And maybe a new level. We'll see.
This release went much smoother than the last two, as I used Panda3D's built-in packpanda to make the installer. I also cut the installer size down by scaling images, deleting unused files, and resampling music and sounds into the Ogg Vorbis format. It's incredible what Ogg Vorbis can do; without sacrificing any quality at all, I cut down the music size by about 20%. With a bit of downsampling, it was about 50%. The final installer is 80 Mb, a far cry from the 176 Mb v0.3 installer!
Anyway, the browser plugin on the website is also up to date. And surprise! A quickie gameplay video. I wish I could record sound in these vids, but alas.