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

Optimization · Pure Optimization
A streamlined click-along action RPG famous for its seamless world.

Optimization · Pure Optimization
Experimenting with doll abilities to uncover multiple solutions to fixed puzzles.
Dungeon Siege leans Optimization (Pure Optimization); Stacking leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Dungeon Siege
Combat mostly resolves itself
Stacking
Hopping between dolls requires no dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dungeon Siege
Mobs charge on simple scripts
Stacking
Puzzle NPCs are static props, not minds
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dungeon Siege
Loot drops vary modestly
Stacking
Doll abilities are hidden until tried once
Dungeon Siege leans a little harder on optimization, though the gap is small.
Dungeon Siege
Party builds and pack-mule logistics are the game
Stacking
Finding every solution per puzzle is the real challenge
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.