Best Online Game World

Counter Strike Source is by far the best online game around the world.
You always have enough players. Also internationally. But for beginners, it is a little difficult to get involved there, because the "other" already longer and better play. But there are servers running play "beginners". Incidentally, you learn it very quickly. And if you already have experience with other games, like the predecessors of CSS or Battlefield or other first-person shooters, it's quite easy. There are plenty of maps that are shown relatively realistic and quite a good selection of weapons. The people look very much real than in Counter Strike Condition Zero and 1.6.
On the whole the game is very well done.
Registering with Steam's totally easy and it can even go. With Day of Defeat Source I personally find it better but with Half-Life 2 I've already played it. Power equally fun.
But for all online gamers and first-person shooter fanatics, or for those who want to be there to be a must.