head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Practiced Mastery
Looking Glass's 1996 squad-command sim of powered-armor combat on alien battlefields.

Execution · Practiced Mastery
An action-leaning stealth entry where aggressive optimal clears replace pure ghosting.
Terra Nova: Strike Force Centauri leans Execution (Practiced Mastery); Tom Clancy's Splinter Cell: Conviction leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Terra Nova: Strike Force Centauri
Piloting powered armor and aiming under fire is demanding
Tom Clancy's Splinter Cell: Conviction
Mark-and-execute flow rewards quick, accurate play
Tom Clancy's Splinter Cell: Conviction leans a little harder on reads, though the gap is small.
Terra Nova: Strike Force Centauri
Enemy forces follow mission scripts, never adapt
Tom Clancy's Splinter Cell: Conviction
Enemies search via scripted last-known-position logic
Terra Nova: Strike Force Centauri leans a little harder on variance, though the gap is small.
Terra Nova: Strike Force Centauri
Unknown enemy placements on first mission attempts
Tom Clancy's Splinter Cell: Conviction
Mild uncertainty in enemy search behavior
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Terra Nova: Strike Force Centauri
Squad orders, loadouts and approach routes are plannable
Tom Clancy's Splinter Cell: Conviction
Encounter rooms have clear optimal clear orders
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.
full breakdown
Terra Nova: Strike Force Centauri →
full breakdown
Tom Clancy's Splinter Cell: Conviction →