head to head
Fallout: New Vegas asks more than Crystal Defenders, and the gap is execution.

Optimization · Pure Optimization
A Final Fantasy tower defense about optimal unit placement against fixed waves.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Crystal Defenders leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Crystal Defenders
No twitch element; placement is deliberate
Fallout: New Vegas
Shooter inputs with VATS assist
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Crystal Defenders
Enemies follow fixed paths, no adaptation
Fallout: New Vegas
Scripted factions and enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Crystal Defenders
Enemy waves are predetermined once learned
Fallout: New Vegas
Some loot and crit RNG
Crystal Defenders leans a little harder on optimization, though the gap is small.
Crystal Defenders
Unit placement and upgrade economy is the whole game
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
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.