This was in HoI3, the black ice mod.
Started as France in '36 reorganised every division, created nice HQ's and positioned them well. Maginot line was mostly protected by garrisons and around 30 regular divisions.
The rest of the army was prepared to invade Luxembourg as soon as Germany captures it, and another part was on the closest route to defend Amsterdam, Bruxelles and Antwerp. The german offensive came strong, at peak managing to capture Amsterdam but then a counterattack of my 7th Army under general De Gaulle managed to push them back.
The British Army was nowhere, I have witnessed the Dunkerque forces retreating instead of helping maintain the line. The struggle was hard but by the end of summer of 40' I was able to contain the attack. Counterattack started in september, north of Amsterdam where the Germans were weak. In the same time I declared war to Italy and conquered Africa (with a minor involvement of the Brits). North of Italy was unbreakable, reinforcements of German divisions stopped my advance next to Turin.
But then, at the end of the year, several Belgium and Netherlands divisions came back from their initial defeat and helped push the front line in Northern Germany to Kiel. In the same time France (me) invaded Norway, pushed away the nazis, conquered most of Denmark (except Copenhagen), so by the June '41 the war looked good, Berlin was near.
Of course it didn't last long. Slovakian, Romanian, Hungarian, Yugoslavian, Finnish and Italian reinforced germans near Hamburg, pushed the line back and forced a retreat almost to the initial borders of Germany. Only the industrial area of Ruhr was held by 40 french divisions. In the same time Germany invaded again Denmark and Norway, taking them back.
War was grim again, brits did not get involved in the western front, France was fighting alongside Belgium and Netherlands. Due to being unable to conquer France, Germany never attacked USSR or Greece.
Short story next:
March '42: Heavy fighting in North of Germany, in the Maginot Line only failed offensives done by both sides. USSR conquers Romania (without declaring war to Axis)
September '42: USA invaded Italy, failed in 3 different points, did ok in Sicily, France landed an army to help against the counterattack. USA did not try to push forward.
October '42: Failed French landing of Yugoslavia, retreat was ok. Successful French invasion of Norway. (for the last time)
March '43: Failed French landing behind the lines in central Italy. Fighting continues in Germany.
March '43: Taking advantage of the fights in souther Italy, and the diversion caused by the failed landing, french forces push the front in Northern Italy up to Venice.
April '43: US troops push ahead just until Anzio.
June '43: French troops push south towards Rome, helping US. Front line is stable in Germany.
July '43: Italy is taken. Time to push forward in Germany.
August '43: US and French forces attack Austria. Canadian and British forces reinforce the western front. Some expeditionary force from Australia and NZ arrive as well.
September '43: France pushes through the Maginot in the south (Mullhouse) with help from paratroopers and tanks lead by De Gaulle and Leclerc.
October '43: US and British landings in Yugoslavia.
November '43: Germany goes all in to defend Hamburg and Munich. Rough weather prevents major offensives.
December '43: Austria is taken.
February '44: Hungary is taken
March '44: Berlin is surrounded.
April '44: Berlin is taken and there is just Eastern Prussia and some Polish territories still standing.
June '44: War with Germany is over. Time to prepare take down of USSR
