This download is the PowerPC OSX installer of Surge from around 2009.
No serial needed, just install and use it in your daw of choice.

It was said Surge is the rival of NI-Massive in features, Surge is a
hybrid FM and Substractive/Wavetable synth.

The author dropped the Surge synth project and released the source
code on github quite a while! Now (as of 2021) the github community
have the Surge Synth as free, currently actively developed and
released for Win64Bit/Linux/OSXIntel64Bit/OSXARM(M1).

Well, this download herer fills the gap for OSX-PPC folks.

System Requirements (Mac)

* Requires Mac OS X v.10.3.9 or later.
* PowerPC Mac with a 1GHz G4/G5 or faster CPU
* 256 MB RAM
* An AU or VST2.4-compatible Host application

Compatibility
Architecture: PPC

PowerPC OSX 10.3.9 or later