Basic gameplay loop is walking around bumping into guys to kill them for money. Most tactical complexity comes from waiting a turn without moving with Z to manage your position, or holding Z to aim your attack on diagonals. You can get a stronger weapon, a ranged one, some magic. Ultimate goal is flying a blimp to the castle in the middle and killing the final boss.
Sorry there was no tutorial or instruction of any kind! I appreciate you taking time to play.