The shield offers the following characteristics:

• 4-operators (sine wave) structure
• 13 different algorithms
• 10 voices polyphony
• 8 simultaneous programs
• Absolute or pitch-relative operators
• 1 ADSR envelope & 1 triangle LFO per operator
• Special operator 4 with feedback and noise features

My Kickstarter page:
https://www.kickstarter.com/projects/1304489933/opa-multitimbral-fm-synthesizer-shield-for-arduino