In addition to Torchlight, I also bought a pack of games off Steam, including World of Goo. Overall I've found it to be a great game, though not without some flaws, or things which I perceive to be flaws. They may be working as intended.
The basic concept is to stick balls of goo together, creating structures which can carry other balls to a pipe at the end. There are many types of goo; some stick together permanently, some can be unstuck, some only stick to one other goo while others stick to as many as they can reach. The world has gravity, and sometimes wind, so you must compensate with counterweight goo, careful construction, and sometimes balloons.
The puzzles aren't quite open-ended. Resources (goo) are limited, so you cannot do much to build in alternate directions. Instead you have to figure out the intended path. In this manner it's not all that different from raiding (as I've experienced them). But it's not a mere connect the dots game.
Onward to the negative: The cost of a mistake is high. High as in, you've spent ten minutes building your structure just right, add one more goo, and down it topples. Some areas have flying buys which will go back one move, but these are limited, and may instead reset your desperate last second shuffling to save the structure, meaning you need to reset over and over. Or you can just let everything topple. If there are no bugs, it is even worse. This lends an air of repetition from failure.
This also gives it a feeling similar to raiding: you run it all perfectly, and then that one mistake takes it all down. You'll better understand it when you see a structure of dozens and dozens of gooballs teeter and topple onto a gear of doom. Wipe.
You can skip a puzzle if you like. I did, when it became apparent that one of them resembled a Mario level more than a puzzle. I don't know how the "spinning horseshoe underwater" level got through testing. It didn't fit the character of the game at all.
Some levels had problems with color contrast, making it hard to see the possible connections against the sky. The internet levels weren't much fun to me, with a large element of "launch some goo and hope it loops around the right way."
The ending was anti-climactic.
I sound as if I hated it, don't I? Well I didn't. It's a lot of fun if you like solving puzzles and building very wobbly structures, which I do. There's even a persistent tower-building area, where you can use a few hundred gooballs to build as high as you want. The game can then compare yours to those of others around the world, which are represented by clouds with a name and country. I had to pull myself away because I knew I'd get taken over by competitive spirit, building as high as I could with a stable design, then experimenting with less structurally sound variants, before it all toppled down and I ragequit.
The pack was $20 and included a few other puzzle sort of games, which I've not tried yet.
All in all, a very fun game, just be sure to expect a raid rather than a faceroll heroic.