free multiplayer online games for iPhone iPod iPad?

https://www.youtube.com/watch?v=Z4caFezKA_8

Found this video on youtube which shows you the best online multiplayer shooting games right now, a lot of them are like playing Call of duty online multiplayer. They are really good games. Have you guys found any other games besides these 6 from the video ? Im looking for games that are similar to Halo for xbox or call of duty type of game, can be paid but better if its free.