head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Optimization · Pure Optimization
A post-nuclear RPG expanded in scope where tagged builds and Gifted-trait optimization dominate.

Optimization · Pure Optimization
A 3rd Edition ruleset combat puzzle where multi-classing and feat selection unlock dominant strategies.
Fallout 2 leans Optimization (Pure Optimization); Icewind Dale II leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 2
Turn-based AP system makes twitch entirely irrelevant
Icewind Dale II
Real-time-with-pause negates twitch requirements
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 2
All tribal and Enclave enemies run fixed scripted combat routines
Icewind Dale II
Scripted enemy routines offer nothing to read or predict adaptively
Fallout 2 leans a little harder on variance, though the gap is small.
Fallout 2
Hidden special encounters and timed events create significant unknown-information space
Icewind Dale II
3E feat combinations and hidden enemy resistances create unknown-information layers
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 2
SPECIAL and skill tagging with Gifted trait produce well-known dominant build strategies
Icewind Dale II
3rd Edition feat optimization and multi-class architecture dominate success
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.