Heatseeker is a guaranteed 20 points of damage if it flies over the enemy tank.
Heatseeker is an excellent weapon choice for early game and when either tank is displaced significantly. If a player is unsure of how much power is needed to reach the enemy, they should guess high. The arch of the missile's path will give the player an idea of how much power to remove without giving up the guaranteed hit.
While heatseeker does not do significant damage, it also does not destroy a lot of terrain, making it useless for digging out of terrain like Dirtball and Mud Pie.