Full 0.1.6 SDK RC1 (binaries, source, samples, documentation) can be downloaded from here.
Most up to date release possible is available in the SVN repository:
To view full list of changes read: release notes.
You can also download nGENE default material set separately:
nGENE Tech material set (put extracted bin folder in your main nGENE folder)
Note: you will also need some additional external libraries. Most of them is included in the nGENE Tech SDK installation package. However, you have to download and install a few more. For more details visit this page.