I do it for multi-player games, MMO's and RTS/turn based games. Basically, if I'm not paying attention to the story, I have music on. The only game this isn't true for is CS but that's because you need to hear footsteps.

There are 1,764,707,400,000,000 different hero combinations in Dota 2 at the moment. Or about 2 quadrillion. And that's just 'picking heroes.' The decision making is so diverse and the range of possible actions is so large. Any game you've seen is going to be unlike any game you've seen before.