It's a second fandisk for Steins;Gate, with several short side stories of a varying quality (from pretty bad to rather decent).What is STEINS;GATE: Linear Bounded Phenogram anyway? Is this a side story of the main game?
(Don't worry, you're not missing out on the first fandisk. The stories there were almost uniformly terrible, only saving grace was a short story where Okabe was gay and boned male Luca)