I get that everyone likes responsive websites these days. You pretty much can't listen to any web designers without the term creeping up, and it's for good reasons, for the most part. Having a single set of stylesheets that work nicely with lots of different viewports is a wonderful thing. But, you have to look further than just how it works. You need to verify that your use case actually does work. 

In the case of Renderosity's market place menu system, it's really not working. 

I challenge you to find one high profile website with half as many menu options....maybe back 10 years ago, but not today. 

Apple? 8 buttons at the top. Not a single drop down menu. True, each goes to a different "site", and they probably have their own set of menu choices, but it's clean and navicable. 

Google? 10 buttons with an eleventh that has about 9 more in a drop down. I'm pretty sure each site has their own menu choices, but..just like with apple, it works well. 

Yahoo? Seems to have ripped google off with the same or very similar layout.  

MSN? OK. MSN comes close to renderosity with a bunch of stuff. But, MSN's site is hardly a high importance site. And it looks pretty much like old yahoo did to me. 

Renderosity? 11 buttons, all but two having many drop down options. 

So, I can live with the annoying maze of dropdowns. I used word, so I understand that sometimes using something can be a pain (as in trying to turn off the little dog that barked at you required hunting for something in some preferences that had hundreds of options. Yes, it's been that long since I quit using word:) Partly because it was a waste of time finding things in preferences.) But, when you make that huge list responsive, then it's even worse. Because I can't just mouse over. And, to make it worse, the size at which it collapses into "phone mode" is about 1/3rd of my 27'' monitor. That's gotto be bigger than an iphone display. I suspect the only reason that it collapses at that size is due to the overly large menu set. 

I think someone really should give some serious thought to the menu system at this site, and maybe spend a week or two just studying some of the really great websites that are out there.