Just a question about feature count. What do you name a feature? a sketch is a feature? or it's just about solid features?
I believe in CATIA in GSD you can make any shape and a closed volume as a single feature in solid
Or even in surface commands it can be low count, mark all the points, and trace a huge 3d polyline on those points, fill the whole thing with surfaces, and closed volume to make it solid. But the tree will be a monster defining all the points, and lines that make the mega fill to generate surfaces.
If low feature count, then i've seen a few using wraps on models, and keeping this representation to ease the hardware as the model was above 10000parts. Or even seen converting to stp and importing again to lose the specification tree as the imported "manifold solid" is only one feature.
I think Fred's intent was to identify innovative solutions to CAD models that minimize the number of steps. I don't consider CATIA's GSD techniques to produce a solid as a low feature count, as I would count the surface and face objects as "features" involving many more steps than using Part Design.
I'm only familiar with SOLIDWORKS, so I can't comment on how CATIA can work.
In the context of SOLIDWORKS, I think we are considering a feature to be an entry in the feature tree. But, if the feature absorbs multiple other features (like a loft absorbing the profile sketches), it is considered a single feature still.
But a plane would be a feature. A non-absorbed sketch is a feature. An extruded boss, or cut is a single feature even though boss work by absorbing a sketch. A fillet is a feature.
We are also limiting these challenges to pretty basic parts. Simple stuff that can be made normally in under an hour. But, trying to make them in the fewest number of features can often take extra time.
These puzzles and challenges are just for fun. I'd never advise anyone to actually make parts with these techniques.