Pardon my newbs showing, but how would you make this tileset larger without sacrificing quality? Also I am using lazy newb pack on Mac.
I am stunned by the beauty and immersion evoked by this set.
You can zoom in and out with the mouse wheel. Changing TEXTURE_PARAM:LINEAR to NEAREST in init.txt should help this look much better. You'll also need to change PRINT_MODE:2D to STANDARD. Yes, this will affect the quality: I usually disable zoom entirely.
Otherwise, no, not unless HaterSkater feels like redrawing the whole thing. Resizing pixel art is different from resizing regular art or photographs: there will always be a loss in quality unless you're precisely doubling it. Well-done tilesets are pixel art: art where the artist has thought about every pixel in their work. When you arbitrarily resize it, you're relying on a program to haphazardly insert more pixels everywhere and hoping the result will look good (it won't). I see people scale tilesets non-linearly anyways using various shaders designed for pixel art, but the result always loses quality (and IMO looks bad).
You can always double the size of this tileset in GIMP or Krita (using "None" or "Box" scaling, respectively). The result will look a bit more blocky (see my own 20x20 sets), but there won't be a loss of quality at all. If you're feeling adventurous, hunt down a program that supports xBRZ scaling--or some other scaler designed for pixel art--then double Duerer using that.
I get the same question sometimes.