Apple's subscription-based gaming service called Arcade just added six new games to its library helping it reach the 100 titles milestone. That's plenty in mobile games standards. The six new games are Sociable Soccer, UFO on Tape: First Contact, Takeshi and Hiroshi, guildlings, Discolored and Marble It Up: Mayhem. The UFO on Tape game, in particular, sounds pretty interesting. It's an AR-based game, which is also a sequel of the UFO on Tape launched back in 2010 for iPhones. It encourages you to look for UFOs in the sky and capture them on video. So if you are into mobile gaming...