head to head
Left 4 Dead asks more than Nuclear Throne, and the gap is reads.

Execution · Twitch Chaos
Co-op zombie shooter whose AI Director reshuffles every run to keep teams honest.

Execution · Twitch Chaos
Frenetic twin-stick roguelike where mutant builds meet unforgiving bullet dodging.
Left 4 Dead leans Execution (Twitch Chaos); Nuclear Throne leans Execution (Twitch Chaos).
Nuclear Throne leans a little harder on execution, though the gap is small.
Left 4 Dead
Headshots, melee shoves, and special-infected reaction time
Nuclear Throne
Twin-stick dodging in dense bullet chaos
Left 4 Dead leans clearly harder on reads.
Left 4 Dead
Versus mode adds human ambush mindgames
Nuclear Throne
Enemies follow fixed behaviors
Nuclear Throne leans a little harder on variance, though the gap is small.
Left 4 Dead
AI Director randomizes hordes, items, and specials
Nuclear Throne
Weapon drops, mutations, and level generation per run
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Left 4 Dead
Team spacing, route choice, and resource discipline
Nuclear Throne
Mutation synergies and crown-route knowledge
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.