head to head
Impossible Creatures asks more than Fallout: New Vegas, and the gap is reads.

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

Optimization · Pure Optimization
RTS where you splice animals into custom armies before battle begins.
Fallout: New Vegas leans Optimization (Pure Optimization); Impossible Creatures 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: New Vegas
Shooter inputs with VATS assist
Impossible Creatures
Standard RTS micro and army control
Impossible Creatures leans clearly harder on reads.
Fallout: New Vegas
Scripted factions and enemies
Impossible Creatures
Human opponents counter your creature picks
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Some loot and crit RNG
Impossible Creatures
Scouting hidden enemy combinations
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
Impossible Creatures
Creature-combining army design is deeply solvable
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.