Artcore refers to more than one genre.
1) Artcore is a mainly underground musical genre that surged in Japan in the 2000s, centered around the beauty of western Europe and the cultures surrounding it. Artcore is mainly prevalent in Doujin circles and Japanese rhythm games. The musical genre was mainly popularized by the Benami rhythm games. It mixes Classical music, Drum and Bass and western European traditional music, and sometimes Trance, Hardcore, Brostep and Electro House. The songs are generally meant to be emotional and use very characteristic emotional atmospheres. They also mix acoustic music with electronic music. The most commonly used instruments are pianos and electric guitars. The song that inspired Artcore is considered to be A by DJ Amuro (more known as dj TAKA), which uses a musical genre called Renaissance which imitates western European music from the 14th and 17th centuries (the Renaissance period) as its name suggests. The first Artcore song is considered to be felys by Onoken, however the term Artcore didn't exist yet at the time, and the first song actually self described as Artcore is Narcisus At Oasis by Ryu☆

2) Hardcore/metal music influenced by contemporary art.