head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Practiced Mastery
Methodically mapping a hostile station where knowledge and routing beat reflexes.

Optimization · Practiced Mastery
The original open-exploration adventure where hidden secrets and dungeon knowledge are everything.
System Shock leans Optimization (Practiced Mastery); The Legend of Zelda leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
System Shock
Combat and cyberspace ask competent but dated reflexes
The Legend of Zelda
Tight sword-poking against aggressive enemies
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
System Shock
SHODAN's threats are scripted, not an adapting mind
The Legend of Zelda
Enemies move on fixed or random patterns
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
System Shock
Citadel's layout and logs are hidden until uncovered
The Legend of Zelda
Hidden caves and burn-every-bush secrets
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
System Shock
Inventory, routing and station knowledge solve the game
The Legend of Zelda
Dungeon order, item routing, and secret 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.