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
A high-intensity wave shooter testing sustained accuracy and stamina against unrelenting scripted enemy hordes.

Execution · Pure Mechanics
Tetris with a puzzle mode - still a test of placement speed and stacking craft.
Serious Sam 3: BFE leans Execution (Pure Mechanics); Tetris Plus leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Serious Sam 3: BFE
Iron-sights mechanics add precision demand on top of classic crowd control
Tetris Plus
Piece placement speed under pressure decides everything
Tetris Plus leans a little harder on reads, though the gap is small.
Serious Sam 3: BFE
All enemies follow scripted wave patterns throughout the campaign
Tetris Plus
Versus mode adds only light opponent awareness
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Serious Sam 3: BFE
Encounter layout is consistent and fully learnable after one pass
Tetris Plus
Random piece order is bounded and rapidly mappable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Serious Sam 3: BFE
Weapon economy and grenade usage offer a thin planning layer
Tetris Plus
Puzzle-mode professor routes have known optimal solutions
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.