head to head
Neither is simply harder - they are hard in different places. Reigns demands more optimization; UNO demands more variance.

Variance · Systems & Chaos
A narrative card game where balancing four meters under random event draws is more luck-management than strategy.

Variance · Pure Chaos
The classic shedding card game where the deck, not the player, usually decides.
Reigns leans Variance (Systems & Chaos); UNO leans Variance (Pure Chaos).
Reigns leans a little harder on execution, though the gap is small.
Reigns
Swiping cards left or right has no skill dimension
UNO
Playing a card requires no dexterity
UNO leans a little harder on reads, though the gap is small.
Reigns
Card characters react to prior choices in semi-scripted ways
UNO
Mild bluffing about held colors and wilds
UNO leans clearly harder on variance.
Reigns
Event card ordering and hidden outcome RNG dominate play
UNO
Hidden hands and the draw pile decide most games
Reigns leans clearly harder on optimization.
Reigns
Learning which choice chains balance the four meters is mappable
UNO
Basic card-retention strategy caps out quickly
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.