GURPSよろず

「巨大化」 nearly always occurs in the context of super-powers or “being a god.” Few other mythic or fictional explanations exist for 「巨大化」, and there’s no realistic rationale for it.
Supers and gods can generally enlarge their equipment as they grow, which calls for the Can Carry Objects enhancement (p. 108).
The GM should permit those with 「巨大化」 to buy 「高速移動」 (Ground) to reflect their vast stride. A reasonable limit is levels of 「高速移動」 equal to half the level of 「巨大化」.
If this 「高速移動」 appears gradually as the character grows, it requires the Size limitation, just like additional ST.
■代替案（Alternatives）
「巨大化」 is for entities that change size. Permanently huge beings don’t have 「巨大化」 (「常時起動」) --they just have a large Size Modifier. High SM is a zero-cost feature for aliens, monsters, gods, and anything else the GM feels should have it. The drawbacks of being an easy target and paying extra for giant-sized equipment offset the discount on the price of ST and HP (the Size limitation; see p. B15).
■パワーアップ（Powering Up）
「巨大化」 suits any power that changes the fundamental nature of matter or moves mass between universes.
It also fits the cosmic powers of deities --and sometimes the divine powers they grant their servants.
Finally, it meshes nicely with the theme of plant-related powers. 才能 doesn’t affect die rolls, but those with multiple levels of 「巨大化」 and 才能 may adjust their SM by up to ±(Talent+1) per second instead of just ±1.