alt Hacker NewsIIRC (from being a kid) Harry was 256 color and DN2 wasn’t quite. Also it felt like it had much better frame rate. But I’m sure that could be engine evolution too. Interesting, I hadn’t ever thought of the connection before.
Though the “hot babes stuck in alien pods” from Harry showed up as a central plot point in DN3D.
I mean, I could be wrong as far as Harry and DN2 sharing an engine, OTOH Apogee did a -lot- of engine reuse (Bio-Menace used a CK4 variant, Monster Bash using an evolved FAST..)
Although, mea culpa, DN1 engine is not necessarily CK but the programmer has credited Carmack in helping with the drawing assembly...