The features are Letter (S/X/O), Size (Small/Medium/Large)
Color (Red/Green/Purple), and Number (1/22/333)
Board 1: XXX S OO OOO S OOO O SS SS
Board 2: S XXX OOO XXX S O
Highest Board Size: 13
This simulation is currently hardcoded to use exactly 4 features and exactly 3 variations (per standard Set rules.) Perhaps in the future I will expand it to deal with a wider range of features and variations.