This question was just (more eloquently) raised by [Xantec](https://scifi.stackexchange.com/questions/32056/what-is-a-good-one-sentence-explanation-for-the-difference-between-steampunk-and#comment60836_32056) in a comment:

> 
> But if you had steampunk technology with modern looking clothing and architecture, **wouldn't that still be called steampunk**?
> 
> 
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(emphasis mine)

For instance, Bioshock springs to mind, which sometimes hints at steampunk-esque technology (think of the freeze-ray/flame thrower or the Rivet Gun from the sequel), but couldn't generally be described as having the classical Steampunk atmosphere.

So, to put differently, is the Victorian-era-like atmosphere (clothing, architecture, look and feel, and so forth) necessary for something to be classified as Steampunk or is the mechanical/steam-driven technology sufficient?