GURPSよろず

see p. B43
This advantage is most suitable for natural creatures that cling to surfaces, and for robots and supers that stick to walls and ceilings using adhesives, magnetism, suction, etc.
Realistic 「壁にはりつく」 for human-sized and larger characters calls for the Requires Low Gravity limitation (below) --but supers are free to ignore this.

■代案
「飛行」 (p. 50) with the -25% level of 「高度制限」 better models the abilities of those who glide along surfaces without touching them.
Individuals who rely on exceptional balance and strength of limb to make seemingly impossible climbs are more likely to have Brachiator (p. B41) and 「超登攀」 (p. 79).

■追加特別増強
Attraction: You can cling to a surface with any part of your body --you don’t need to assume a crawling posture.
You can walk “upright” along a vertical surface, leaving your arms free, or even hang from the top of your head or your back in order to use all of your limbs. +25%.

■追加特別限定
Requires Low Gravity: Your ability doesn’t function in gravity fields over a certain, maximum strength.
For humans, this is typically 0.6G. -5% per 0.1G under 1G (-5% for 0.9G, -10% for 0.8G, and so on --down to -50% for 0G).

■パワーアップ
「壁にはりつく」 is often mediated by some kind of attractive force, making it suitable for such powers as 「サイコキネシス」, Gravity, and Magnetism (with the Magnetic limitation).
An equally common explanation is the ability to form a bond with a particular substance.
This requires the Specific limitation (p. 112), and is appropriate for elemental powers --Earth power in particular.
才能 adds to all ST, DX, and skill rolls made to negotiate obstacles or stop a fall.