How to play — rules of the original, and how combat works here
Goal. Win by occupying all five power points at once, by destroying every enemy piece, or by leaving the enemy with nothing but imprisoned pieces. Light moves first.
Movement. Ground pieces move orthogonally (never diagonally) up to their range and cannot pass through any occupied square. Flyers and the teleporting Wizard/Sorceress move in any direction up to their range and may jump over pieces. No piece may land on a friendly piece.
The luminosity cycle. 27 squares oscillate through six shades — black, dark, barely dark, barely light, light, white — and back, shifting after every other turn. A battle on a light square favors Light; on a dark square it favors Dark. Pieces on power points heal at the start of their owner's turn and are immune to enemy spells.
Combat (the one change from 1983). There is no arena. When a piece attacks, each side's effective power = weapon strength (Force × attack pace, from the original manual's stats) × current health × luminosity modifier (±12% per shade step). The attacker wins with probability proportional to the two powers. The loser is destroyed; the winner keeps the square but takes damage scaled by the loser's power — and a winner can be dragged down with its victim, just as both fighters could die in the original arena.
Spells. The Wizard and Sorceress each know seven spells, each castable once per game: Teleport, Heal, Shift Time, Exchange, Summon Elemental, Revive, Imprison. An imprisoned piece cannot move until the oscillating squares reach the shade of its own side (a piece trapped on a fixed enemy-colored square may never be freed). The Shapeshifter fights with the strength and vitality of whatever it faces.