In the arts, radically new and daring

• Trend-setting, perhaps
• Unorthodox, untraditional leaders
• Pushing the envelope
• Like experimental art
• Original advantage involved in capturing king
• Group on the cutting edge
• Like John Cage's music
• Like the work spelled out by the shaded letters
• Eye cover for the naive?

Wiktionary Word definitions in Wiktionary
n. (alternative form of avant-garde English)