This is hands down my favorite game on steam. I simply can’t wrap my head around all of the polish and creativity stuffed into this game. The writing is funny, interesting and clever. The plot twist in the middle of the game is brilliant and caught me by surprise the first time I played trough the game. The list goes on...
Portal 2 features a lot of new mechanics that improve on the first game and makes this game feel fresh and exciting.
The aerial faith plates make for some fast thinking while in mid air. The light bridges are not so interesting alone, but when they are combined with cubes, gels, and aerial faith plates the can be used for some really fun puzzles.
My favorite of the new additions might be the gels. These are mostly used in the latter half of the game and they are really fun. Just like the faith plates these enable some really fun fast paced gameplay and some interesting puzzles, when used right. There are four gels: repulsion, propulsion and conversion gel. These in this order: make you jump/bounce high, make you run fast, make any surface portal compatible, clean the earlier mentioned gels of objects or walls.
The single player campaign is around 8 hours long and kept me hooked all the way trough. The biggest difference between the original Portal and its sequel in my opinion is how the game changes your perspective on it the further you go. At first it seems like GLaDOS is the main antagonist but just around 3 hours in the tables get turned and your ally Wheatley gets mad with power, throws you and GLaDOS down a hole. The visual style now changes and new gameplay additions get added as you explore the old Aperture Laboratories. Now instead of GLaDOS being your enemy you now do the tests of the former owner of Aperture, Cave Johnson. GLaDOS now fills the spot of Wheatley and Cave Johnsons pre-recorded messages will provoke you as you try to solve all the tests in the underground. The longer you progress longer into the underground tests the older the tests will become.
The game changes up audio, visuals and puzzle mechanics all the way to the end which allows it to continue without being repetitive. Even the loading screen changes to represent the old aperture.
Except for the single player campaign Portal 2 also offers a lot of new additions: an in-game level designer, a full co-op campaign that is playable both in split screen and online and a challenge mode. The part about the level editor that makes it so great is that there is multiple ways to create levels. Valve has made its easy with an in-game editor but it is also possible to use the way more powerful Hammer editor which is what was used to make the full game. With the power of the full editor some amazing maps have been made. A fact that may surprise a lot of people is that Portal 2 has the most populated workshop on Steam. With over 300 000 community maps you can almost play this game forever.
I especially recommend you try out the gelocity maps made by a steam user called Radix. These maps turn the game into a racing game in which you use the portal and ping mechanics to screw over your opponent as well as take shortcuts. These are insanely fun to play with a friend.
Since this game is at this time over 8 years old it is often on sale and is very easy to run on most hardware. To give you some perspective on how easy this game is to run: my 7 year old thin and light laptop can run this with no problems.
I advise most people to play the original Portal before the sequel since there's a lot of spoilers and references in this game. Overall these games are awesome on top of that they don’t even cost 10€.