I've been slowly adding to my list of relaxing, (mostly) casual puzzle games that I can play both to wind down or get the brain active, and my current list consists of - Kami, Ichi, and Lyne. Of those games, Lyne is easily my favorite, and one that I see myself playing over and over, for the rest of my life. The daily challenges add a lot of replayability to the game.
If you like circuit-based puzzles, you will really enjoy this game.
The aesthetics are very simple, but also very easy/nice on the eyes. Different shapes of varying color on a basic background make for relaxing gameplay, completely at your own pace. There isn't really any music, however, the sounds made when you clear a level is very soothing, and when you get in the zone, clearing levels very quickly provides good, positive feedback. After you complete several levels, you unlock the ability to switch the background theme to different color palettes, unlocking more options as you progress through the game.
The controls are super simple - you just click and drag the mouse to move your circuit to (applicable) areas on the grid. The learning curve is minimal to moderate, however, the higher-difficulty levels can be extremely challenging. Difficulty is indicated by the number of triangles.
Each "set" of levels consists of 25 levels, and there is one set for every letter of the alphabet (26). On top of that, there are daily challenges that are changed throughout the week, starting at the easiest difficulty on Mondays, and increasing to brutal, oh-my-god-just-kill-me-this-is-so-hard-and-I-haven't-slept-yet-trying-to-finish-this-level torture on Sundays. Achievement hunters will have a grand time trying to 100% complete this, and I play this regularly whenever I have some time to fill. As mentioned before, I see myself playing this game for the rest of my life.
The goal in Lyne is to get all same-shaped circuits to connect to each other - the two bold shapes are your start and end points (you cannot miss a non-bold shape, and you cannot continue the circuit if you connect the start/end points). As you progress, more colors/shapes will be added, increasing the difficulty. Nodes will eventually appear (double, triple, and quadruple sockets), and these must be filled completely for you to solve the level. Nodes are also critical in the later stages, as they will allow your circuits to cross otherwise uncrossable pathways (ex: if you have a green connection going diagonally, you cannot have other circuits passing through that diagonal line). You can undo your connections at will with no penalty, and there is no time limit - everything is completely at-your-own-pace.
One of the best attributes of this game is how it rewards patience, perseverance, and trial-and-error. Many times, I have solved a puzzle by trying every possible route/solution I can think of. Other times, I will go back a few levels and have a sudden moment of clarity because you will realize that most levels in set follow very similar "themes" to solve the puzzles. For example, one set may have a pattern of having you use the longest path (or the shortest path). There are numerous ways to solve each level, and this is also a great thing, because it ensures that you have multiple ways to complete each level.
Overall, this is a great puzzle game that any puzzle enthusiast must try out - especially if you like circuit-based ones.
DJSF @DJSF's Rogue Reviews