Hexiom Connect is a very simple, but very elegant, puzzle game which manages to be very difficult without being unfair. The result is a game that (at least if you solve it honestly, like me) can keep you occupied for quite a long time and still remain interesting.
Hexiom Connect is kind of a successor to Hexiom (which, while I have played, I haven't yet reviewed here, and may never, since it's so difficult), but really the only thing the two have in common is that they're puzzle games played on a grid of hexagonal tiles. In Hexiom Connect, you have a bunch of tiles with colored paths on them, and the object is to place the tiles so that all of the paths link up with each other properly. Some levels have some tiles which are already fixed in place (which serve as a handy starting point for your deductions), but some have no fixed tiles. The game contains 30 levels, all of which are very well-designed, as well as a random level generator which lets you generate endless levels of your chosen size and other specifications.
A lot of the earlier, smaller levels can be done by trial and error, but when you get to the larger and harder levels, trial and error alone will not suffice (unless you're very lucky!). You'll need to use logic, which mostly consists of finding places on the grid where only one (or maybe two) tiles can fit, and then building outward from these known tiles. The interface helps to some degree -- you can use shift-click to lock a tile in place if you know it has to be there -- but I found myself really wishing for a couple of features. First, it would be really nice if there was some way to, say, control-click on a hex and it would show you all of the tiles that could be legally placed on that hex. It would also be nice if you could somehow drag tiles off the board so you could get a better view of what you knew and what you didn't.
The graphics are pretty basic -- the paths brighten up when they're connected properly, which is nice, but it also means that the color of the dimmed paths can occasionally be difficult to distinguish. The tiles also get awfully small on the bigger levels -- I spent a lot of time squinting at my monitor before discovering that you can make the game bigger by increasing the text size on the page (at least in Firefox; I can't speak for other browers). I really love the music; it's very beautiful and has just the right feel for the game. Unfortunately, there is only one track, so even though it's great, you will likely find yourself tiring of it on the longer levels.
Hexiom Connect is not an easy game -- some of the harder levels took me more than an hour and required me to keep a lot of notes about the possibilities and things that I'd already tried, but I was glad to complete it without having to rely on any walkthroughs (although I'm sure if you're lazy, you can easily find solutions -- you'll just have to live with your guilt). Overall, it was a very satisfying and enjoyable experience, so if you're looking for a good puzzle game, give Hexiom Connect a try.