head to head
Neither is simply harder - they are hard in different places. Game Dev Tycoon demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
Optimizing game development decisions around hidden genre-topic match formulas to maximize review scores and revenue.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Game Dev Tycoon leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Game Dev Tycoon
All choices are menu clicks with no physical ceiling
Portal 2
Portal placement requires some precision but timing is lenient.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Game Dev Tycoon
No adaptive human competitor to model
Portal 2
No opponent; puzzles are static.
Game Dev Tycoon leans clearly harder on variance.
Game Dev Tycoon
Review scores and trend timing have meaningful randomness
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans a little harder on optimization, though the gap is small.
Game Dev Tycoon
Genre-topic-audience matching and R&D investment are learnable formulas
Portal 2
Solving the puzzle's logic IS the entire game.
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.