head to head
Castlevania III: Dracula's Curse asks more than Half-Life 2, and the gap is execution.

Execution · Pure Mechanics
The hardest NES Castlevania, with branching routes and switchable partner characters.

Execution · Pure Mechanics
Landmark FPS built on physics puzzles and tight gunplay.
Castlevania III: Dracula's Curse leans Execution (Pure Mechanics); Half-Life 2 leans Execution (Pure Mechanics).
Castlevania III: Dracula's Curse leans clearly harder on execution.
Castlevania III: Dracula's Curse
Brutal platforming and tight whip timing throughout
Half-Life 2
Gravity gun and shooting demand precision.
Half-Life 2 leans a little harder on reads, though the gap is small.
Castlevania III: Dracula's Curse
Scripted enemies and bosses only
Half-Life 2
Combine AI scripted, non-adaptive.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania III: Dracula's Curse
Minor enemy spawn wobble
Half-Life 2
Almost no randomness.
Castlevania III: Dracula's Curse leans clearly harder on optimization.
Castlevania III: Dracula's Curse
Partner choice, route branching, pattern memory
Half-Life 2
Linear progression with no builds.
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.