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

Optimization · Pure Optimization
A wave-defense RTS testing economic and defensive optimization against scripted hordes.

Optimization · Pure Optimization
A park management puzzle where understanding the guest happiness formula lets you solve each scenario optimally.
Diplomacy is Not an Option leans Optimization (Pure Optimization); RollerCoaster Tycoon 2 leans Optimization (Pure Optimization).
Diplomacy is Not an Option leans a little harder on execution, though the gap is small.
Diplomacy is Not an Option
Fast unit micro helps but isn't the ceiling
RollerCoaster Tycoon 2
Track building is grid-based with modest placement precision demands
Diplomacy is Not an Option leans a little harder on reads, though the gap is small.
Diplomacy is Not an Option
Enemy hordes follow scripted waves, not adapting
RollerCoaster Tycoon 2
Guest behaviour follows fixed preference scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diplomacy is Not an Option
Some map and event variation, mostly fixed
RollerCoaster Tycoon 2
Very little randomness once ride stats are understood
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Diplomacy is Not an Option
Economy, defenses and army composition against scaling waves
RollerCoaster Tycoon 2
Pricing, ride stats, and park layout are near-perfectly 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.