Disharmony: Horatio didn't cause the Success mission and crash by extension. The Argosy still crashed (probably because of the Endless defense installations), carrying OpBot on it. The events of EL occur, but with none of the additional content. In this timeline the Vaulters can't repair the Argosy but manage to discover ancient ship designs that they eventually use to leave the planet. The Broken Lords rebuild the Grey Owl and use it to leave, unsuccessfully. Dust is purely an Endless invention. Advanced technology is mostly kept by nomadic spacefarers before the events of ES1, drastically reducing the amount of factions and causing the few planetbound nations that achieve interstellar travel to quickly dominate the political landscape.

Vodyani: The events of DoTE and the Horatio Comic occur, driving the survivors underground. Both Guardians, Shifters and maybe Tempest are canon here but not Forgotten. The existence of dust at an earlier point drives the tipping point for the Endless to drive Harmony influence away and radically change the political landscape of the Dust Wars, enabling a much more common distribution of advanced technology which causes many technological nations (most importantly the Vodyani) to exist at all. Several of the factions that rule the galaxy in Disharmony are marginalized by this fact and possibly also by their apparent dependance on the Endless. ES2 only happens at all in this timeline.

Forgotten: OpBot ends up on the Success instead of the Argosy, which somehow influences Horatio to "win" Dungeon of The Endless, causing them to become the Mezari on the surface instead of evolving into Vaulters, all content packs are canon here. Horatio may have also been responsible for the creation of the Forgotten. The ultimate fate of the Mezari is unclear, but they probably end up escaping without archeological assistance.

It should be noted that a lot of certain cultures and individuals end up on a similar path but at radically different points in time, possibly because of relativistic influence. However, Horatio achieving his dominion in either the United Empire or Mezari empire suggests that the one in Disharmony is actually one of his clones, which explains why he's an objectively inferior being with an apparent tolerance for opposite gender clones (maybe this one's also a intersexed genetic chimera?)