head to head
Neither is simply harder - they are hard in different places. StarCraft II: Wings of Liberty demands more execution; Yu-Gi-Oh! Duel Links demands more variance.

Execution · Grand Arena
Real-time strategy where hands, reads, and build optimization all matter at the top.

Optimization · Grand Arena
A fast-format digital Yu-Gi-Oh! card game built around ranked PvP and meta decks.
StarCraft II: Wings of Liberty leans Execution (Grand Arena); Yu-Gi-Oh! Duel Links leans Optimization (Grand Arena).
StarCraft II: Wings of Liberty leans clearly harder on execution.
StarCraft II: Wings of Liberty
APM, macro, micro-control under pressure
Yu-Gi-Oh! Duel Links
Tapping cards, no dexterity test
StarCraft II: Wings of Liberty leans clearly harder on reads.
StarCraft II: Wings of Liberty
1v1 ladder vs adaptive humans modeling you
Yu-Gi-Oh! Duel Links
Ranked PvP rewards predicting set cards and bluffs
Yu-Gi-Oh! Duel Links leans clearly harder on variance.
StarCraft II: Wings of Liberty
map spawns minor; mostly known
Yu-Gi-Oh! Duel Links
Draws and unknown opponent decks dominate
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
StarCraft II: Wings of Liberty
build orders, economy curves heavily solved
Yu-Gi-Oh! Duel Links
Meta deckbuilding and line calculation are the spine
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.