I think with Portals. Truly.
The original Portal, is quite simply, one of the best games ever made. Its narrative is appropriately vague, tight, and absolutely hilarious. The gameplay is also equally as brilliant. Portal 2 takes all the qualities of the original, and somehow manages to expand upon them. Valve takes the Portal series from a memorable, and somewhat peculiar game, to a series that is as innovative as Half-Life before it.
Portal 2 is simply Portal evolved, it takes the bits and pieces of Portal that made it so great and expounds upon them. For example, Portal had enough gameplay mechanics to count on one hand, while Portal 2 introduces a myriad of new mechanics, systems, and toys to play with that all enhance the gameplay experience, without convoluting the simple nature of Portal. All of these new mechanics are intelligently introduced, test chamber by test chamber, while simultaneously ramping up the difficulty. This is quite an impressive feat, considering Valve introduced new mechanics such as, propulsion gels, lasers, light bridges, tractor beams, and plenty more. All of these are introduced while also not making the player feel overwhelmed in the slightest. Of course, the now simple mechanics that were introduced in the original Portal, buttons, cubes, and well, portals, serve as the backdrop to the fresh batch of stuff that Portal 2 introduces.
However, all of the new mechanics are the not even the most exciting part of Portal 2. There are two new characters, Wheatly: the Personality Sphere (voiced by the hilarious Stephen Merchant) , and Cave Johnson: the founder of Aperture Science (voiced by J.K. Simmons). Both of these characters are as well written and as intelligently hilarious as any character, including the internet-famous GLaDOS. Speaking of the murder-loving robot from the first game, she is (of course) still in Portal 2, and while I don't want to spoil some of the best moments of the game, she makes a very strong return. This increases the list of characters to three, and while that isn't an impressive number, it is very impressive that all three contribute to the game in meaningful ways, and without them, the game just wouldn't have nearly as strong of a personality as it does. Oh and the game is also twice as funny as the original, in case you were wondering.
Unlike the original Portal, Portal 2 breaks the white-test chamber format for the most, and while there are still plenty of test chambers, the game changes out the environments constantly. The Aperture Science Enrichment Facility has plenty of secrets to it and you will explore nearly all of them. This means a lot more environmental diversity, from your basic white-test chamber, offices, and even to a myriad of different blown out caves. This really helps give the game an even greater sense of progression, as you can tell that you are not progressing just by the number on the test chamber, but also by the new environments you discover.
Of course, these environments wouldn't be such a blast to see and do puzzles in if they didn't look appealing. But no need to fear! The six-year old Source Engine is back, and it looks great. While you wouldn't mistake it for Cryengine 3, the terrific lighting really helps immerse you in the mad science world of Aperture Science. As expected by Valve, the voice acting and writing is some the best in the business, and without it, this game would suffer greatly.
There is also a Co-Op Campaign, which I have yet to play a lot of, but of what I've played so far, it seems as though it would be even more furiously entertaining as the single-player campaign. There is a really clever ability that allows the player to "tag" a spot for his partner so that you can tell your partner where to shoot a portal, instead of blindly telling your partner to "Shoot it here". It's a really great innovation, but it seems as though a headset, or voice chat of some kind, is a near necessity in the co-op.
When it comes down to it, I can honestly only think of one problem with Portal 2, which would be the frequent, but often brief load times. That's honestly it. Ihonestly can't think of any other flaws with the game. It's that good. Buy it, play it, love it.
Actually, I thought of another flaw: It ends.
Five potatoes out of five.
