Top 10 Free to Play Games on Steam

It's been a while since Steam first published a Free to Play game and, by now, its collection of freemium games has grown significantly. Here is a partial list, according to Steam's Most Popular (Free to Play games) tab:

1. Team Fortress 2 - That's right: in case you didn't know, TF2 is absolutely free! It's also supposed to be the most highly rated free game of all time.
2. Stronghold Kingdoms - I haven't played this one, although I did play Stronghold 3. It's supposed to be the first MMO of it's kind.
3. APB Reloaded - I already gave this one the 2nd place in my Top 5 Free to Play MMOs list, so it's not surprising to see it here in the third place.
4. The Lord of the Rings Online - Based on the reviews I've read about this one, it's in the fourth place only because of the general popularity of LOTR.
5. Star Trek Online - As with the previous title, this game probably wouldn't have been in this top if it wasn't for how popular the TV show was.
6. Alliance of Valiant Arms - I've never even heard of this game before, but it's about the Soviet Union and, considering the amount of Russian free2play gamers, it's no surprise this game has gotten so popular.
7. Spiral Knights - We're getting to the part of the top where the titles begin to sound like gibberish. This is the 2nd one I haven't heard of.
8. Super MNC - This is supposed to be a fun casual game. The first part of the trailer shows a massive man falling in love with a girl, while butterflies fly around them. The second part probably shows them getting into a fight or something.
9. Realm of the Mad God - Never heard of this title either. Not interested in hearing of it again either. Problem? :)
10. Fallen Earth Free2Play - I actually even played this one and, while the whole idea behind it is great, it does look better on paper.

 Now I've only added a quick note to each of the titles, so feel free to defend the honor of your favorite game from this list. I will totally be objective about it. :))