Edit: Good news -> now most of these items are visible (listed by the API): see a couple of posts below
I'll start a list of "hidden" bundled game ids, since there seem to be quite a few around:
************** Hidden bundled products (not listed in the products API) **************** *
1275264927-> Humans 3: Evolution - Lost in Time -> part of
The Humans Bundle *
1297948342 -> Sudden Strike 3 The Last Stand -> part of the
Sudden Strike 3 bundle
*
2134842136 -> Sudden Strike 3: Arms for Victory -> part of the
Sudden Strike 3 bundle
*
2083140130 -> Ken Follett's The Pillars of the Earth -> first book I assume, part of the
Ken Follett’s The Pillars of the Earth - Season Pass bundle
*
1358826905 -> The Journey Down: Chapter One -> part of
The Journey Down Trilogy *
1391062119 -> Humans 2: The Jurassic Levels -> part of
The Humans Bundle *
1443986935 -> Sudden Strike 2 -> part of the
Sudden Strike 2 Gold bundle
***************************************************************************************** I'll keep this updated on a regular basis... I'm sure there are more to come.
Edit: Added
Humans 2: The Jurassic Levels.
Edit: Added
Sudden Strike 2.