"FreeBoard", re-using a lot of Board logic, but with SVG (empty) board + SVG (empty) reserves.
Will be used for variants with custom non-rectangular board (Hex, at least)
Or, with other board shapes (see greenchess.net for example)
+
+=====
+
+New variants:
+Hidden2: Hidden with free initial setup (as in Screen)
+Shinobi Chess