If you look at the art in my Microlite75/78/81 games, you've probably noticed that I tend to use public domain line art, either from old books or from the sets of art Sine Nomine Games has released into the public domain. However, this means I end up reusing a lot of art from publication to publication. Given that I can't afford to pay for art as my games are freebies, this probably is not a surprise to many readers.
If I wanted to use photographs, there are literally hundreds of thousands of photo available on the web with Creative Commons Zero or other very liberal Creative Commons-style licenses that allow modification and commercial use. Unfortunately, photos really do not fit the style I'm aiming for. I have been trying programs that convert photos to sketches on and off for several years. Unfortunately, most either are so "sketchy" that you can't tell what the drawing is of or so detailed that they look more like half-toned pictures than line art. However, last week I stumbled on a program on my Android tablet that does a decent job of converting photos to drawings -- especially if I do a bit of pre-processing of the photo before I use the sketch filter.
Here are fifteen examples of photos converted I have converted to drawings by this process. The original photos had a public domain like license (that only prohibited releasing the unaltered photos as a collection). I'd like to know what people think of "drawings" like these for using in old school gaming projects. If people like them and think they would be useful for people who need free art of old school games, I will do more of them in the future. If I did 10 or 15 a week, within a few months, I could have quite a collection available. These samples are suitable for fantasy games, but I would not always limit myself to fantasy.
I understand that these drawings will not appeal to those who believe that every game (even free ones) need original art done especially for that game. However, many hobbyists designing games cannot afford this. Also, note that the originals of these images are much larger and these larger illos would be the ones I make available for people to use in their publications.