Developer OtherSide Entertainment, the studio led by Deus Ex and Thief: The Dark Project creator Warren Spector, has revealed that its upcoming stealth adventure game, Thick As Thieves , will only cost $4.99 when it launches on Steam on May 20. Alongside this pricing news, OtherSide has detailed its plans for the game, highlighting that the initial content offering at launch will be an "introductory campaign."  This introductory campaign will feature 16 missions set across two replayable maps and six pieces of gear to unlock. OtherSide says the campaign will run at least four hours, but is just the beginning of the studio's plans for its 1900s alt-history city of Kilcairn. The studio says its intention is to expand the setting and the stories of Thick As Thieves in future content, according to a press release.…