Though complicated and convoluted, Portal 2 takes one solid idea and runs with it until the very end. In today's Speak Up on Kotaku, commenter Fernando Jorge wonders why more games can't follow in Portal 2's footsteps.
Portal 2 shows games could use more simplicity. Not all games, not all genres, but I'd say a lot of games could be way simpler.
In Portal 2 you can just jump and open portals and the game takes this basic mechanic as far as it can go. The end result is a game that is very tight; there are barely any loose ends.
On the other hand, take Fallout, Mass Effect, Dead Rising, Grand Theft Auto, all of them enjoyable and very good games but a lot more complex than Portal. All of those games have numerous issues, things that just don't work right, that are frustrating, that are useless.
If a game focuses on as least elements as possible while trying to get the most out of them the result will be a flawless game. I don't mean to use the word flawless as meaning best game ever; I mean it as a quality for a game. To be polished.
Take Tetris or Super Mario Bros. as an example. Very simple and nearly flawless. But what often happens with games is like... if someone developed Chess and then decided to add 4 more pieces, make the pieces have HP, customizable abilities and create multiple different boards