head to head
Assassin's Creed IV: Black Flag asks more than Red Dead Redemption 2, and the gap is optimization.

Optimization · Practiced Mastery
An open-world pirate adventure where upgrading the Jackdaw matters more than the blade.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.
Assassin's Creed IV: Black Flag leans Optimization (Practiced Mastery); Red Dead Redemption 2 leans Execution (Practiced Mastery).
Red Dead Redemption 2 leans a little harder on execution, though the gap is small.
Assassin's Creed IV: Black Flag
Naval broadsides and boarding need modest timing
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
Assassin's Creed IV: Black Flag leans a little harder on reads, though the gap is small.
Assassin's Creed IV: Black Flag
Multiplayer deception mode; campaign is scripted
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed IV: Black Flag
Weather, convoys, and hunting spawns
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Assassin's Creed IV: Black Flag leans clearly harder on optimization.
Assassin's Creed IV: Black Flag
Ship upgrades and fleet economy drive progress
Red Dead Redemption 2
Loadouts and routes solvable but loose.
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.