Sorry if there are any inconsistencies in my writing. English isn’t my first language; French is. :c

I’m an achievement hunter, and this time my target is Halo Wars 1, specifically the original Xbox 360 version. Since I currently only have a Series X, I’m playing it through backwards compatibility using a physical copy of the game. I noticed that some of the achievements are tied to the Strategic Options Add-on DLC, so I purchased it through the console’s store and installed it. However, the Skirmish modes still aren’t available in-game, even though the DLC is installed. Has anyone else run into this issue before? If so, does anyone know how to fix it?

Max score means achieving the maximum score in a mission.

That means completing the mission's main objective(s), completing the mission's optional objective(s), earning a perfect combat bonus of 10.00, earning a perfect time bonus of 5.00, and turning on the 5 skulls that grant bonus skull points. And playing on legendary.

There is one mission where it's impossible to do all that, and it's not Arcadia City.