Short, puzzles don’t change on subsequent playthroughs, no multiplayer. Minimal enemies, methods to defend yourself, and methods to accomplish a goal.

And of course it falls into the same huge problem that all full-on puzzle games always fall into. If you just have no clue what to do, you’re not gonna figure it out. If you’re not looking at the puzzle the right way, no amount of trial and error is going to get you the right answer.

And if (heaven forbid) you look up the answer, that’s half the point of the game removed!

That’s what I like about the Deus Ex series. There isn’t just a few possible answers to a complex question. You can puzzle it, sneak it, shoot it, blow it up, or use any combination at any magnitude you want! And that’s present in spades in Human Revolution!

None of that is to say Portal is a bad game, or that Human Revolution is flawless. But you asked.