These scenarios are not real. The better ones are designed to give you some possible military options to experiment with. That's all. They aren't intended to let you correct all the perceived moral failings of political leaders seventy years ago. You can't do that. It's too late. If you're so concerned with what you perceive as gross injustice in the world, then I suggest you focus on current events instead. And computer games have no impact whatsoever on either historical or modern reality. You need to get into the real world to have chance of any sort of impact.
I should apologize. That comment was not a criticism of your scenario, which I have not played.
The point is not just to remedy injustices that have already occurred. It is to think about the alternatives and possibilities, Yes, Yalta is a done deal, but what malfeasance, laziness, naivety or other factors led to the historical outcome, and how might changing this part of the story change or fail to change the outcome. And a total reversal is hardly necessary.
It's the possibilities that excite me, and why I engage with games. The goal is not to win but to hone an ability for lateral thinking. This kind of the historical use of games like chess and Kriegspiel, Diplomacy and maybe even Stratego. Even Monopoly, when played as intended is supposed to be a teaching mechanism about how capitalization rewards winners to make them impossible to fail and punishes those with bad luck to ignominy no matter their skill. The game IS unfair, that is the point. I'm not simply interested in scenario design because I'm a player, but ever since I had a horrific run-in with tabletop roleplaying, I've been fascinated by the notion of game design and how it can be used to not only teach, but to get people interested looking things up, thinking about new possibilities.
In the case of Market Garden, when I say, what does it matter? That's not a criticism of choosing this scenario to create. Rather, it's more philosophic. Germany is done for in late 1944, Hitler has decided on what he will do, the German Resistance is dead, there's no reason to think he will surrender even if the Allies get into the German plain in late 1944. If the Allies beat the Soviets to Berlin, what of it? Patton beat the Soviets to Prague and Allied command promptly handed back to Soviet administration.
These are important questions, not in terms of answers, but in process, In foreign policy, broadly, Liberals fear creating a Treaty of Versailles, the conservatives for creating another Munich. But unless you really wrestle with the context of the era, you'll never understand the contexts of why both were inappropriate in their time. And thus you cannot truly learn from the past.
And I ask in all good faith: why did you create this scenario? What I think it is you believe that these games are about (a private) glory, and I hold that these games are all about teaching that war is the continuation of politics by other means. Am I right in that?