Dune II didn't have an engine name, it pretty much invented the whole modern RTS genre (Herzog Zwei was a prototype for the genre, however) and much of it was b

Dune II didn't have an engine name, it pretty much invented the whole modern RTS genre (Herzog Zwei was a prototype for the genre, however) and much of it was bespoke/non-general code. For C&C and RA they had the "Westwood Engine", C&C2 & RA2 used the "Westwood Engine 2"; both of these (and the Dune II prototype engine) were also referred to as "the Command and Conquer Engine". They then had a small gap of 3D games (Renegade, for instance) that used the "Westwood 3D" engine which was expanded and renamed to "SAGE" for Generals. All followup C&C games used "SAGE 2.0".