Why are the 1st edition Monster Manual giants so small? Did Gary want to make sure that everything was killable? In the AD&D Monster Manual, a Storm Giant had 15 HD, three less than a T-rex. And they were only 21 feet tall.
Let’s embiggen these guys.
Take the giants from your favorite monster manual and multiply their hit dice and height by a factor of eight to twenty, depending on your tastes. Me, I’d make them maybe ten to fifty times taller (Storm Giant would be 210 – 1050 feet tall).
The bigger you make them, the easier it would be to sneak up on them. It would also be harder for the giant to hear them. And they need more to eat when they eat.
Give them attacks that do tremendous area of effect damage with fists or thrown objects (trees, boulders, the tops of small hills…). Armor class should be ten, but any attack doing less than HD/10 HP isn’t felt and has no effect (unless you stab them in the eye).
Movement is trickier. If there is no significant obstacles, then a running giant would have a stride of about 1.14 times his height. So each step would be .507 his height. So for six second rounds, you could say he moves height x 1.14 if you assume that it would take six seconds for one stride. Which seems slow to us, but remember the terrain isn’t likely to be flat and giants would need to be careful not to fall. A one minute round would mean they move height x 1.14 x 10. A ten-minute turn would be height x 1.14 x 100. I am guessing that the opportunities and need for the largest of giants to run are few and far between, so you can cap it if you want.
Sample size/HD/movement rates:
Labyrinth Lord Hill Giant, XL (x5)
60 feet tall, 40 HD, Moves 68 feet/six seconds, 115/ ten seconds, 685 feet/minute
Labyrinth Lord Fire Giant, XXL (x 10)
160 feet tall, 110 HD (+20 HP), Moves 182 feet/six seconds, 304 feet/ten seconds, 1828 feet/minute and 18280 feet/ten minute turn. So in ten minutes, over three miles.
Labyrinth Lord Storm Giant XXL (x20)
420 feet tall, 300 HD, Moves 478 feet/six seconds, 800 feet/ten seconds, 4800 feet/minute and 48000 feet/ten minute turn. Nine miles in ten minutes! If he could run nonstop, he could circle the Earth in less than 19 days.
So what’s the point, really? At this point, these are forces of nature. They are tougher than the divine beings of Deities and Demigods–Why stat these guys in the first place?
Two words: Monster fights. More soon.