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 · Practiced Mastery
A gritty WWII Call of Duty that introduced the Zombies mode.

Execution · Practiced Mastery
Artillery aim under wind combined with fort economy planning against human opponents.
Call of Duty: World at War leans Execution (Practiced Mastery); Worms Forts: Under Siege leans Execution (Practiced Mastery).
Call of Duty: World at War leans a little harder on execution, though the gap is small.
Call of Duty: World at War
Twitch gunfights in fast multiplayer lobbies
Worms Forts: Under Siege
Manual trajectory aiming under wind decides each shot
Worms Forts: Under Siege leans a little harder on reads, though the gap is small.
Call of Duty: World at War
Human opponents reward positioning prediction
Worms Forts: Under Siege
Human opponents to outguess on building and target priorities
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: World at War
Random lobbies, spawns, and zombie waves
Worms Forts: Under Siege
Wind, crates and terrain damage randomize turns
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: World at War
Perk loadouts and map control are learnable
Worms Forts: Under Siege
Fort placement and weapon-tech economy reward planning
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.