head to head
Neither is simply harder - they are hard in different places. Command & Conquer: Red Alert 3 demands more execution; SpyParty demands more reads.

Reads · Grand Arena
Three-faction Cold-War RTS with naval combat where faction asymmetry and multi-front pressure are the core tests.

Reads · Pure Mind Games
A spy performs missions at a cocktail party while a sniper studies the crowd for one inhuman tell.
Command & Conquer: Red Alert 3 leans Reads (Grand Arena); SpyParty leans Reads (Pure Mind Games).
Command & Conquer: Red Alert 3 leans clearly harder on execution.
Command & Conquer: Red Alert 3
Naval and air micro alongside base-building taxes player bandwidth
SpyParty
Sniper aim and spy input precision matter at high level.
SpyParty leans clearly harder on reads.
Command & Conquer: Red Alert 3
Three-faction asymmetry means opponent choices must be constantly predicted
SpyParty
Pure 1v1 behavioral modeling; both players adapt endlessly.
SpyParty leans a little harder on variance, though the gap is small.
Command & Conquer: Red Alert 3
Ore spawning and naval choke variance add moderate uncertainty
SpyParty
Mission sets and partygoer randomness add modest noise.
Command & Conquer: Red Alert 3 leans a little harder on optimization, though the gap is small.
Command & Conquer: Red Alert 3
Production order and defensive placement are learnable but more flexible
SpyParty
Tells, timings, and mission orders reward deep study.
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.