Disclaimer: This is a preliminary review, I have not completed the game yet, but I would estimate my progress to be about 20% give or take, with an active playtime of about ~15 hours, which already means that this game has a lot to offer content-wise, and so far it was a great experience throughout.

Update: Finished the game, but had no time to write a review yet that does it justice.
Can recommend to the fullest extent! Buy it! But also play the first game, it will all make much more sense!

Outdated preliminary review
Here are the short versions of each category below.

Graphics: Stunning, gorgeous, really. A lot comes down to the general aesthetics of the design, but there are a lot of "advanced" graphical options present which were not in the first game.

Performance: Is is OK, I can feel though that my RTX 2080 is becoming just a tad bit "mediocre" at running new titles. I am mostly getting a stable 60 FPS+ at 1440p however, so it is fine for this type of game.

Gameplay: An interesting blend of "traditional" puzzle gameplay à la Portal and more open style exploration with a sense of wonder at uncovering the secrets and meanings of the surroundings, tied together by a (so far) very intriguing storyline, with multiple characters.
There are a lot of similarities in the puzzles to the first game, but many things have changed or expanded upon (like the laser puzzles), so it feels very fresh.

Story A love letter to all the explorers, thinkers, tinkerers, scientists and dreamers alike.
Without spoiling too much, it is (so far) a great continuation to TTP 1's storyline, again filled with many philosophical questions & theories, with time for contemplation, reflection and theory crafting. This time around you're not on your own in the world though (as was the case in TTP 1 were all interactions were constrained mostly to terminals), you can interact and talk with different characters & companions to make sense of it all.

World / level design Incredible, breathtaking, awe-inspiring. That is basically all I can say about it.

Sound / Music: The sound design is good & immersive, but the star of the show is the (once again) excellent soundtrack accompanying the game. I really do hope they will release this one again as download.

Overall: I am tentatively already calling this a masterpiece, in every possible way. And it is a game that resonates with me on a great level, just as the predecessor did.
The madlads at Croteam really seem to have done it, they have made an incredible and logical follow-up to the first game.

Disclaimer: This is a preliminary review, I have not completed the game yet, but I would estimate my progress to be about 20% give or take, with an active playtime of about ~15 hours, which already means that this game has a lot to offer content-wise, and so far it was a great experience throughout. [b]Update:[/b] Finished the game, but had no time to write a review yet that does it justice. Can recommend to the fullest extent! Buy it! But also play the first game, it will all make much more sense! [b]Outdated preliminary review[/b] Here are the short versions of each category below. [b]Graphics:[/b] Stunning, gorgeous, really. A lot comes down to the general aesthetics of the design, but there are a lot of "advanced" graphical options present which were not in the first game. [b]Performance:[/b] Is is OK, I can feel though that my RTX 2080 is becoming just a tad bit "mediocre" at running new titles. I am mostly getting a stable 60 FPS+ at 1440p however, so it is fine for this type of game. [b]Gameplay:[/b] An interesting blend of "traditional" puzzle gameplay à la Portal and more open style exploration with a sense of wonder at uncovering the secrets and meanings of the surroundings, tied together by a (so far) very intriguing storyline, with multiple characters. There are a lot of similarities in the puzzles to the first game, but many things have changed or expanded upon (like the laser puzzles), so it feels very fresh. [b]Story[/b] A love letter to all the explorers, thinkers, tinkerers, scientists and dreamers alike. Without spoiling too much, it is (so far) a great continuation to TTP 1's storyline, again filled with many philosophical questions & theories, with time for contemplation, reflection and theory crafting. This time around you're not on your own in the world though (as was the case in TTP 1 were all interactions were constrained mostly to terminals), you can interact and talk with different characters & companions to make sense of it all. [b]World / level design[/b] Incredible, breathtaking, awe-inspiring. That is basically all I can say about it. [b]Sound / Music:[/b] The sound design is good & immersive, but the star of the show is the (once again) excellent soundtrack accompanying the game. I really do hope they will release this one again as download. [b]Overall:[/b] I am tentatively already calling this a masterpiece, in every possible way. And it is a game that resonates with me on a great level, just as the predecessor did. The madlads at Croteam really seem to have done it, they have made an incredible and logical follow-up to the first game.