head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Pure Mechanics
Pure aim and movement skill tested against adaptive human opponents competing for spawn-cycle dominance.

Execution · Competitive PvP
Lab-honed combo execution plus live mixup guessing against adapting human opponents.
Quake III Arena leans Execution (Pure Mechanics); Skullgirls: 2nd Encore leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Quake III Arena
Rail and rocket aim at speed is the entire game
Skullgirls: 2nd Encore
Long combo routes and tight conversions demand serious hands
Skullgirls: 2nd Encore leans a little harder on reads, though the gap is small.
Quake III Arena
Human opponents adapt their routes and timings in direct response
Skullgirls: 2nd Encore
Mixups and resets only work by out-guessing a human
Quake III Arena leans a little harder on variance, though the gap is small.
Quake III Arena
Spawn locations have mild randomness but are quickly mapped
Skullgirls: 2nd Encore
Fully deterministic fighter with nothing hidden
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Quake III Arena
Armor and weapon timing routes are learnable and highly leveraged
Skullgirls: 2nd Encore
Team composition, assists and combo theory go deep
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.