oak falcon
So, there's a game I used to play a long time ago. It's probably rather dated by todays standards but it featured Siege combat in a way that I absolutely loved and have yet to see replicated in a similar way.
The game is Viking: Battle For Asgard
It was a game I originally played on the Xbox 360, although it suffered from lag issues, however playing it on a modern PC system seems to get rid of those issues (your experience may vary)
What I loved about the game was it was an Open World (by the Xbox 360 era standards) game, and right from the very beginning your tasks are simple, rescue Vikings that have been enslaved to grow your army, take back locations of high value and importance (Mines for weapons, Farms for food, Forts that had become enemy strongholds) that sort of thing.
I don't know exactly how much of it actually contributed beyond required goals but the endgoal was always the same, once you've amassed all the required strategic locations and grown your army large enough, you engage in large scale Sieges on the major Enemy locations. I don't know if the Evolution Engine is capable of the same level of enemy density, but I think capturing the feeling would be enough.
My only flaw with the game is that it's Linear, you got three major Landmasses and there's no real replayability beyond starting a completely new game, but with how Soulframe handles locations being reset. I think if such a similar thing was done in Soulframe, it'd be perfect due to replayability of Sieges.
Some bonus things I'd like to point out while on the topic of this game.
It didn't have a traditional Day/Night cycle, instead it was dictated by whose territory you're in. If you're in player controlled/liberated territories it'd be bright and sunny.
If the locations were enemy occupied, they'd turn to night and stormy. I think the latter would fit with the Ode.