I don't see how you can install only a fraction of the game and still play on it. I sort of understand with singleplayer games like HL2 where there are only a few models and textures and maps at the start, and download as you go. However, say you were downloading TF2, surely you'd need all the data if you wanted to play online at all.

But yeah, nice deal with the free Rome: Total war, though I don't really want it.