Largest scale battle I've ever won was in real life, actually. Patong, Thailand, 2006.
It was Thai new year. Of course, they tend to celebrate this by having every single person in the region pick up a watergun, take to the streets and start blasting eachother.
Thailand happens to be a popular tourist destination for Australians; Needless to say, they were out in force. And they were teaming up. We (Me, my father, a sports centre owner and his two sons, and a taxi driver, all British) were sitting outside a café just after dusk when the aforementioned warband came into sight at the end of the street. Many of them, it seemed, had taken to pouring red dye into their water tanks. We thought they'd pass by us, but we were wrong; what could have easily been twenty of them turned towards the cafe and opened fire. Or, er... Opened water.
We barely had time to grab the waterguns that had been lazily resting against the legs of the table before we were diving for cover, trying to avoid the streams of red-coloured water already soaking the front of the café.
I managed to get behind a low wall, while most of the others opted for ducking behind large potted plants or hiding behind pillars. We returned fire quickly, careful not to expose ourselves for two long, until they gave up and returned to the horde making its way down the main street and slowly spreading out. Finishing our drinks as quick as we could, we made a mad dash across the street and realised that it was a hell of a long walk back to the hotel we were all staying in.
I think the rest pretty much speaks for itself in an almost Left4Dead-esque manner. It was definitely one of the more interesting holidays I've taken.
If we're going into videogame related battles only, then they'd have to mostly lie with Arma 2 or Empire Total War.