Could be either or a mix of some conquest going fubar and them being forced to backtrack to another planet/location to restock and rebuild due to something happening during the long travel or they came against more resistance than they expected for the next species on the chopping block.

And for the latter, I can imagine if the Elders don’t retreat, they tap into those psionic gateways to access the other conquered and secured planets to get at the resources they stockpiled.

A couple more XCOM OC refs: Leon and Detlef! I am starting to vibe with this layout for character refs lol we'll see how long it lasts

Vipers are tricky to draw. It's mostly the head shape and the hood I think. Anyway Detlef's colour scheme comes from the blue racer snake, because blue racers are pretty

Also I didn't intentionally give Leon the same name as the pilot from the Bureau (not that I'm sure I've even seen anyone mention that character because the Bureau is only ever talked about because people like/theorize around Asaru lmao), but it does feel appropriate/ironic/funny to me to have a guy with a related ethnicity from the other side of the iron curtain have the same name (I say this because Bureau!Leon is one of two characters to mention the Cold War during the course of the game/use the word "Commies" in relation to Russians lmfao)