7 years old though.
Firebird
I bought this a while ago,
Great little synth and I`d guess one of the best freeware VSTis around now!
It’s a little too old-school sounding for me, but I haven’t had much chance to really play with it yet.
no linux version? 
Yep, it’s old. And this is only x86 version. It doesn’t work well with Cubase x64 (6.X/7.X checked) - several crashes of Cubase bridge/wrapper. IMVHO, fine VST for 32bit hosts, I’ll try it with Renoise later this day.
I’ve been playing with it in Renoise recently, and you can do some pretty cool stuff with it. For a free vsti, you really can’t go wrong with this one starting out. I’m not a huge fan of the way it quantizes its rhythms with the gating and etc, since I like to put my BPM up at around 400 to get higher resolution rather than using the LPB.