I selected my class and now I'm on the screen where you customize your name and appearance. But the Accept, Back and Options buttons don't work! I can change my name and appearance but none of the other buttons are working so I can't leave the screen. What is going on?

Oddly enough, I've run into this same issue (OS X Yosemite 10.10, MacBook Pro Retina 15-inch Late 2013, NVIDIA GeForce GT 750M). First time I've hit a show stopping bug so early with an unmodified install... and I'm kinda disappointed to see that there have been no comments.

Since your post is a couple months old, did you happen to find a workaround?

Fixed (the ugly way)—See Below

For anyone else encountering the problem of not being able to load past the character creation screen, I was able to "fix" it, but not using GOG's Wineskin built version.

None of the usual hacks worked, nor did upgrading the wrapper software or wine engine, so there may be an underlying problem with the packaged game files themselves. Unfortunately, regardless of graphics mode (opengl/gdi or fullscreen/windowed/virtual), the wine logs provided no useful data at the hang point, so I built a new wrapper from scratch to compare the installs.

It looks like the GOG dev team used Wineskin Winery 2.5.8 with the WS9Wine1.5.23AMDSpeedHack wine engine. None of the standard Winetricks modifications I tried on their build worked, so I investigated a few other wrappers—including the one on PlayOnMac, which worked with the old GOG installer but not the latest one (the installer crashes)—and technical reviews from WineHQ/AppDB.

The largest number of success references were to Wine 1.4.1 so that's what I opted to go with (supposedly 1.6.2 works as well). Unfortunately, just swapping out the wine engine used in GOG's Nox.app package had no effect, nor did upgrading the Wineskin wrapper to a newer version (2.6.0)... so as previously mentioned, there may be an underlying game files issue with GOG's current Mac version of Nox (1.0.0.10)...

Getting to the point...

How to create a functional Nox via Wineskin for Mac OS X (tested on Yosemite 10.10):

(1) Download the Windows version of Nox from GOG (currently version 2.0.0.20)
(2) Download and install Wineskin Winery 2.6.0
(3) Run Wineskin Winery and install the engine WS9Wine1.4.1
(4) Create a New Blank Wrapper named Nox.app
(5) In Finder, Show Package Contents (via Ctrl+Click menu) of Nox.app
(6) Run the contained Wineskin.app
(7) Under the Advanced section, use Tools > Winetricks to:
* Install the gdiplus DLL
* Set ddr=gdi
(8) Click Install Software button (at the bottom of the Advanced window) and select the Windows Nox installer exe file you downloaded earlier.
(9) Complete the installation, agreeing to the EULA and using the installer defaults—if you can't see the buttons, just use the Enter key to progress through each screen.
(10) Set the runnable Windows EXE option to use NOX.EXE
(11) Click Set Screen Options and change the following (click Done when finished):
* Override Wine control of Screen Settings? - Override
* Override Settings - Fullscreen
(12) Click Test Run to see if everything worked correctly—if so, you're done—if not, review above.

As an aside, you can convert the gfw_high.ico icon file in the nested Nox game directory to a Mac compatible format (ICNS) using something like iConvertIcons (has an online web-based converter) and set the resulting gfw_high.icns file as the Wineskin icon in the Advanced > Configuration tab.

Additional Note:
Setting ddr=gdi isn't strictly required, and it will likely make the video scenes choppy and difficult to watch. Instead, you can set ddr=opengl, which will make the videos play more smoothly, but may also add some vsync issues / screen tearing during gameplay at lower resolutions. If you prefer to use ddr=opengl, I recommend playing at 1024x768 instead of 640x480.