[ravenfish]

Thoughts:

With a 1938 setting, the first obvious question is of course what the Nazis are up to. Are they looking for the Holy Grail and Ark of the Covenant, or are they too busy building flying saucers?

People are going into space. How are they getting there? Accelerated rocket development? Superscience antigravity or reactionless thrusters? Really big cannons?

The insistence on the phrasing "largely No Mana worldline" raises the question of what's going on in the bits that aren't. Do you have plans for occasional actual sorcerers or at least a mysterious cult or two in magical regions, or are you just keeping options open?

When you say "relatively high historical inertia until recently", how "recently" is recently? If Wells's Martians invaded in 1895, things have certainly been very weird for at least that long- or were they hushed up somehow?

Why is Sex as a power source something that needs to be explicitly called out as not part of the default setup? I must be reading the wrong GURPS books...