The 8x8 board

The 8x8 board is the hard board. A round on it starts with a seed word across the middle row, and you make 7 plays from a rack of 7.

Difficulty
Hard
Cells
64
Premium squares
13 (21% of the board)
Exotic square types
4 of the 14, chosen per board
Plays
7
Tiles in the bag
30
Rack
7 tiles

Which premium squares a board carries, and where, changes from puzzle to puzzle; the counts above do not.