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.

Execution · Twitch Chaos
GameCube kart racer with two riders per kart trading items mid-drift.

Execution · Pure Mechanics
An action racer where players detonate the environment itself to wreck rivals and reroute the track.
Mario Kart: Double Dash!! leans Execution (Twitch Chaos); Split/Second leans Execution (Pure Mechanics).
Split/Second leans a little harder on execution, though the gap is small.
Mario Kart: Double Dash!!
Two-character swaps and drift timing
Split/Second
Drafting, drifting and dodging collapsing set pieces.
Mario Kart: Double Dash!! leans a little harder on reads, though the gap is small.
Mario Kart: Double Dash!!
Item duels against humans reward baiting
Split/Second
Timing powerplays against human rivals rewards prediction.
Mario Kart: Double Dash!! leans a little harder on variance, though the gap is small.
Mario Kart: Double Dash!!
Special item rolls swing races
Split/Second
Triggered explosions and route changes upend races constantly.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart: Double Dash!!
Character pairings and lines are solved
Split/Second
Knowing every trap and shortcut converges with play.
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.