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

Optimization · Pure Optimization
A vault management sim about optimising dwellers, rooms, and resource loops.

Optimization · Pure Optimization
A fragmented-timeline mystery that asks players to reconstruct causality across escape-room puzzles.
Fallout Shelter leans Optimization (Pure Optimization); Zero Escape: Zero Time Dilemma 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.
Fallout Shelter
Tapping menus only
Zero Escape: Zero Time Dilemma
No physical demands in escape rooms or choice screens
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout Shelter
No opponent
Zero Escape: Zero Time Dilemma
Fragment-based story has no adaptive opponent
Fallout Shelter leans a little harder on variance, though the gap is small.
Fallout Shelter
Incident spawns and lunchbox loot rolls
Zero Escape: Zero Time Dilemma
Non-linear fragment order and hidden outcomes obscure the path
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout Shelter
Dweller stats and room layout are fully solvable
Zero Escape: Zero Time Dilemma
Connecting all fragments to reach the true timeline is a logic puzzle
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.