head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; Planetbase demands more variance.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.

Optimization · Pure Optimization
Engineering self-sustaining closed-loop life support systems on a hostile planet against scripted environmental events.
Fallout: New Vegas leans Optimization (Pure Optimization); Planetbase leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
Planetbase
Building placement is unhurried and menu-driven throughout
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
Planetbase
No adversarial AI; threats are scripted event types
Planetbase leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
Planetbase
Solar storm timing and resource availability add hidden pressure
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Planetbase
Power and oxygen loops are tightly engineered optimization puzzles
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.