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 turn-based 4X strategy game about optimizing civilization growth and tech trees over centuries.

Optimization · Pure Optimization
Base-building strategy game about optimizing upgrade economy and raid compositions.
Call to Power II leans Optimization (Pure Optimization); Clash of Clans 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.
Call to Power II
none, purely turn-based decisions
Clash of Clans
Troop drop placement is forgiving
Clash of Clans leans a little harder on reads, though the gap is small.
Call to Power II
limited prediction of AI civ behavior
Clash of Clans
Base layouts anticipate human attackers' habits
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call to Power II
random events and combat outcome rolls
Clash of Clans
Matchmaking and unseen traps add uncertainty
Call to Power II leans a little harder on optimization, though the gap is small.
Call to Power II
deep civilization-building and tech optimization
Clash of Clans
Army comps, upgrade paths, and attack routing
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.