In yet another attempt to creating art-assets I'm not quite sure about the underlying technique. The game is a 2D game that is being built using opengl and textured quads. The screen resolution of this game can vary and this causes me lots of headache.

Should I base my graphics on vectorgraphics due to scalability? I could then give every resolution the appropriate texture, making it all look crisp.

Should I base my graphics on large Photoshop files? I could downscale them all, however lower resolutions will require some bit of optimizing

Or should I assume one "standard" resolution and simply let the opengl-filtering doing all the filtering (probably bad looking)?

Any suggestions or examples would be appreciated.

What's your target device- mobile or desktop? I have little experience in mobile, but with desktop you'd be pretty safe to look up the most common resolutions and aim for visuals which will satisfy the most people. The Steam hardware survey is great for this and, well, I'll just tell you what it shows: Most people have one or two 1920x1080 monitors on the high end, but there's a significant number of laptop users at 1366x768. Those two resolutions are pretty much what you have to target, aside from a few (vocal) enthusiasts with super premium displays.

How do you feel about upscaling and seeing the pixels? Sounds like you're not of fan of that approach. Leaving it to some other sort of filtering is probably not going to look good unless you're really careful; imagine seeing little blurry bits contrasting with sharp bits all over depending on how something was rotated or scaled. I wouldn't advise it unless you've got a sound plan to handle rendering.

Perhaps you think of some examples of games whose visuals you like? When I think vector graphics, I think of World of Goo (for example), which did pretty well. Simulating the look of vector art with large raster files is, I think, inefficient and will almost certainly create weird scaling artifacts. And if you can work around that, you might as well have made the graphics vectorized and done effects in rendering.

... The more I think about it, the more it sounds like you want to do vector graphics based on what you've written. I actually don't have any practical experience doing vector graphics for games, so I'll just leave it at that thought.

Thanks for your advice. It's going to be primarily a desktop-game but it should also work on mobile devices. The game itself uses pixel-graphics but I thought maybe doing the basic outline of art-assets in a vector-based program (before working out the details in Photoshop) will help optimizing graphics for each resolution.

The more I think about it "fluid" scalability and crisp 2D graphics seem to not match very well unless as you said, one can handle the downsides of engine-filtering. If the displayquality of 2D pixel-graphics have a high priority, I think there's hardly a way around determining exactly what resolutions will be supported and then putting some extra handwork in optimzing.