Depending on the rules set, you can have a game that doesn't end. The Axis controls Eurasia and Japan while the Allies control everything else. The income is about equal and the Allies have sufficient naval and air power to prevent the Axis from expanding while the Axis has sufficient land power to counterattack and destroy and Allied landings.
@LaFayette I hadn't really thought about it like that but I'd say that's a very accurate assessment. The deciding factor in my games that go on for longer seems to be who can better keep their front reinforced by securing the supply route and keeping men coming timely. I found that most of my troubles come from not building and deploying reinforcement units as quickly as I should or by redirecting some reinforcements to a less important region which costs the main front.
Long response here, but this is how I think about it FWIW:
TripleA is a game of competing supply lines. There can be multiple fronts and you can "feed" the different fronts at different rates with a supply line. An opponent has an opposing set of supply lines that compete against yours. There is a push and pull as the supply lines do not have to matched and both players are trying to create an imbalance to gain a tactical advantage where they can advance their front. When a front advances, you gain more income, your supply line lengths, but so does your income per turn and the rate at which you can send units down that supply line. So for example, while I might be next door to Moscow, it takes 4 turns to feed that front, I can feed it with 5 tanks per turn to more than match Russia building 4 infantry per turn. This means sitting outside of moscow, after 4 turns, I'll get 5 tanks added compared to 4 infantry.
The multiple fronts is where it gets interesting, if axis really need 4 turns sitting outside of Moscow, where is the pacific front? Would Japan have those 4 turns to be able to hold its supply lines and not fall before then?
TripleA is really interesting as the supply lines are dynamic and can be adjusted down or up and shifted. Ultimately both players are trying to create an imbalance so they can advance along a front.
Ultimately all victories are going to be supply lines victories. The question comes down to recognizing which supply lines are won and which ones matter more than the other.
Going back to the question, certain maps have a certain period of time when the supply lines tend to play out and generally the outcomes become clear. Sometimes it's sheer persistence for one player to play out a front until the full tactical advantage has come about. Because battles are probabilistic, it's not guaranteed a single round advantage will hold. For example, allies might need 1 turn to get odds on Tokyo, and 3 to get decisive odds. Axis might need 2 turns to get odds on Moscow. If the battle of Tokyo goes bad, then the axis will get their 2 turns. If the battle goes well, then the Axis will not. In some games though the axis front will be matched & stalled, which means an imbalanced supply line in the pacific will lead to Tokyo falling, which then means the US can open a new front and would then completely imbalance the existing German supply lines causing a defeat there.
TL:DR, the size of maps dictates the length of supply lines, maps tend to require a certain number of turns for supply lines to play out. Very even players will balance each others supply lines leading to late round games, uneven players will create a decisive win on one or more fronts while holding others, meaning they'll win the game once the supply line has minimally played out.
Comebacks are almost impossible because games ara cumulative considering territories have actually 2x value than what they are marked, it is just mean refuing to surrender in this point and unnecessarily prolonging.
That's why I'm thinking there should be a draw option to prevent games pratically end in the middle of nowhere anti-climaticly.
As far as I researched, no matter which WWII game, the victor usually start to appear in rougly r10ish which I consider the last round in this topic.