head to head
Neither is simply harder - they are hard in different places. Half-Life 2 demands more optimization; WarioWare: Touched! demands more variance.

Execution · Pure Mechanics
Landmark FPS built on physics puzzles and tight gunplay.

Execution · Pure Mechanics
Touch-screen reaction speed against a randomised barrage of microgames.
Half-Life 2 leans Execution (Pure Mechanics); WarioWare: Touched! leans Execution (Pure Mechanics).
WarioWare: Touched! leans a little harder on execution, though the gap is small.
Half-Life 2
Gravity gun and shooting demand precision.
WarioWare: Touched!
Instant stylus reactions to five-second prompts are everything
Half-Life 2 leans a little harder on reads, though the gap is small.
Half-Life 2
Combine AI scripted, non-adaptive.
WarioWare: Touched!
No opponent - just escalating microgame speed
WarioWare: Touched! leans clearly harder on variance.
Half-Life 2
Almost no randomness.
WarioWare: Touched!
Random microgame order demands instant recognition
Half-Life 2 leans clearly harder on optimization.
Half-Life 2
Linear progression with no builds.
WarioWare: Touched!
Each microgame is trivially solvable once recognised
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.