The opening "He are sent on mission" was on purpose I'd assume.
Yep! All the cutscenes in the game are written as a sort of tribute to the translation (or lack thereof) of the earliest NES titles. The death message is similarly written as the same kind of parody.
Am I wrong to say that the song in the promo video seems heavily "inspired" by the Moon song from Duck Tales?
Probably not a big surprise, but you're spot on! The song in the promo is actually the background music within the game that plays during Assimilate's own moon levels. The moon is the last section you conquer in the game. And the directive I gave my composer for the background music on those levels was, naturally, take inspiration from the Ducktales moon music. The Ducktales moon theme is one of the finest pieces of music in gaming history, and I love what my composer was able to do with his own moon theme here.
Does anyone else find it impossible to read the word "assimilate" in anything but a robot voice?
Ha! Didn't realize it had that effect on people! Very cool!