I don’t disagree with you, Collector. Since SierraGamers is Ken Williams’ site, i doubt he’d want to focus on games which his company did not develop. Since Coktel Vision, Impressions, Dynamix and so on were acquired by Sierra, they were also part of Sierra. Games developed by acquired studios under Ken Williams’ management should therefore in my opinion also be considered as developed by Sierra, even though it was not done so by the people in Oakhurst.
However, this brings several more questions: 1) what about games which were developed by those companies before Sierra acquired them (Operation Wolf, Detroit,When Two Worlds War,…)? Should those count as Sierra games? 2) what about games which were published by Sierra, but not developed, nor acquired in the early days (Thexder for example, for which Ken bought the rights from GameArts to sell it in the USA in the mid 80ies)? 3) what about the games which were developed after Sierra’s demise, but by an acquired studio (for example the citybuilding series by Impressions, the Tribes series by Dynamix or the later Nascar titles by Papyrus)? It is very hard to draw a line.