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

Optimization · Pure Optimization
A survival city builder driven by harsh resource and law optimization.

Optimization · Pure Optimization
Optimising colonial economy and revolution timing on an unknown map.
Frostpunk leans Optimization (Pure Optimization); Sid Meier's Civilization IV: Colonization 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.
Frostpunk
Pausable strategy with no input precision.
Sid Meier's Civilization IV: Colonization
Turn-based clicks - no physical layer
Sid Meier's Civilization IV: Colonization leans a little harder on reads, though the gap is small.
Frostpunk
No adaptive opponent in the survival city.
Sid Meier's Civilization IV: Colonization
AI rivals follow mappable tendencies
Sid Meier's Civilization IV: Colonization leans a little harder on variance, though the gap is small.
Frostpunk
Scenario events and weather pulses add tension.
Sid Meier's Civilization IV: Colonization
Map generation and exploration hide early information
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Frostpunk
Resource routing, laws, and heat are solvable.
Sid Meier's Civilization IV: Colonization
Colony economy, specialists and independence timing are deeply solvable
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.