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

Execution · Pure Mechanics
The full-band rhythm game whose setlist and feel made it the genre's high-water mark.

Execution · Pure Mechanics
Tests frame-tight jump timing through fully memorisable obstacle sequences.
Rock Band 2 leans Execution (Pure Mechanics); The Impossible Game leans Execution (Pure Mechanics).
The Impossible Game leans a little harder on execution, though the gap is small.
Rock Band 2
Guitar, drum, and vocal accuracy on expert charts
The Impossible Game
One mistimed jump restarts the level - perfect inputs win alone
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Rock Band 2
Charts never respond
The Impossible Game
Solo - nothing to predict
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Rock Band 2
Fixed setlist charts
The Impossible Game
Levels are identical on every attempt
The Impossible Game leans a little harder on optimization, though the gap is small.
Rock Band 2
Overdrive activation paths decide leaderboard scores
The Impossible Game
Memorising the jump sequence is half the climb
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.