Assuming not much has changed I can see a few differences:
- The UNSC (known as the Union of Socialist Star Systems or USSS) would have the military either disbanded or defunded heavily, either way the covenant war would be force a rearmament. I imagine the war would be as disastrous as the Gold Timeline albeit a little less
- The Sangheili and other species would probably be more hostile to humanity after the war due to communism.
- Any captured Covenant technology can be reverse engineered faster due it not being gatekeeped by greedy private corpos and civilians being allowed to test with de-tracked materiel (de-tracked because Rubble).
- The biggest difference I can see is the tension between Earth and Outer Colonies being less prevalent due to democratic centralization.
That’s all I can see. Idk what would be of the Halo Array or The Flood or Banished, whatever.
If the tensions between the outer and inner colonies weren’t as high, then there wouldn’t be a spartan program before the covenant war, so humanity would’ve been double fucked at the beginning of the war.
A socialist government may have been significantly more advanced due to factors like this.
I think the bigger point in the OP is that humanity may have de-militarized entirely. I don’t know enough about the Halo universe to get into that one.
There’s Halopedia if you want a cursory glance though you need to get actual expanded universe material like the Halo Encyclopedia in order to get a deeper understanding.
There’s no material reason to militarize because there’s barely any threats. At most the USSSDF would be a glorified peacekeeping force. That said if the USSS were to discover the Halo Array I imagine things would go similarly to how it was in the og timeline - including the Flood outbreaks.
Yeah. The situation would be more desperate I imagine. I imagine the Halo Array being discovered would be even more important by the events of CE.