was any sequel of the game made?
Yes, Thirty Flights of Loving
Gravity Bone
A sequel to "Gravity Bone", "Thirty Flights of Loving", was announced as a reward for contributing to the Idle Thumbs podcast revival Kickstarter. 
what is gravity bone? A freeware adventure game who developed it? Blendo Games. for which platform was it made? The game was released for Microsoft Windows.
wiki:25550796
Gravity Bone [SEP] Sequel
A sequel to "Gravity Bone", "Thirty Flights of Loving", was announced as a reward for contributing to the Idle Thumbs podcast revival Kickstarter. The game was released to Kickstarter backers in July 2012, and later offered as a purchasable title on Steam, which included "Gravity Bone" as an additional feature. The game, though not a direct sequel in story to "Gravity Bone", follows the main character in a heist with two other characters that goes very wrong. The title was critically acclaimed by reviewers, who called the very short but non-linear storytelling of "Thirty Flights" a novel use of the video game medium.