The game is cool, but the in-game instructions lack. There are 3 things to note:
(1) Although the instruction seems to suggest either killing the undead king or standing your ground, it is impossible to kill the king as Move Points don't recharge and your units can't reach him.
(2) 'Move' Points aren't actually for movements. Instead, any unit that runs into enemies while consuming Move Points are invincible and deals much more damage.
(3) You can tramp on two units with one 'move'.
After you notice these facts, the game is simple: Maximize your Move Points, always try to make moves that hit 2 enemies, make orders after the undeads are reanimated, and perhaps learn the hidden orders.