To understand POWDER, you should first understand roguelikes. “Roguelike” is a term applied to a wide variety of games which share a common inspiration from the game Rogue. A non-exhaustive list of such games would be: ADOM, Nethack, Crawl, Diablo (I & II), Moria, and Angband.
Powder is not a port of an existing roguelike. It is built around replayability and long term ergonomics, not short term learning. It uses actual graphic tiles (16×16) rather than the traditional characters.