Ryu Knight is based on an anime series of the same name. The story of the game is simple: you are Adyu, an apprentice knight who spends all his time training. One day, a mysterious old man appears out of nowhere, approaches Adyu and tells him the world needs more paladins, and therefore you must train harder in order to become one. He sends you on a quest to find a legendary weapon, which is broken into twelve parts, each part being hidden in a different place. He also entrusts you with the power of Ryu, a huge magical armor that grants the hero who equips it immense power. This is where Adyu's journey begins!
The game is an action RPG, somewhat similar to the Ys series. Adyu wanders through the world and fights enemies in real-time combat, using melee weapons. He can also jump to avoid enemy attacks. You gain experience after defeating monsters and advance in levels. You can summon the armor Ryu at any time, which makes you much stronger, but you can't go through narrow corridors and climb up stairs when in Ryu form. The game features mostly open areas populated by enemies with an occasional town thrown in. The structure of the game is non-linear: you can visit almost any area of the map at any time.