Osmos is a unique little indie that I quite enjoy. Osmos is an ambient puzzle game where you play as a cell absorbing other cells. You can only absorb cells that are smaller than yours. If you glaze the side of a larger cell, you'll lose matter at a rate proportional to how much is cell is touching, and a head on crash will see your cell instantly absorbed. To move, you must jettison some of the material from your cell. You click to spray a little, click rapidly to make minute adjustments, and hold for bigger bursts of thrust. All movement is physics based, including the movement of all other cells. Movement, positioning, and timing are the three aspects most used in these puzzles. By this I mean to say that since you only have a limited amount of movement, sometimes you will have to be frugal with your fuel/size and be patient until an opportunity to absorb your next target comes around. Besides the click to move system, there's a few other handy controls you'll want to know. First of all, in this game, you can actually control the rate at which time passes. If you hold ctrl+scroll with the mousewheel, you can adjust to exactly whatever rate you want, which is great because sometimes I found myself scrolling it back and forth often for speeding up time as I crossed empty spaces, and then slowing it down a lot as soon as I got close to an object, or otherwise had to wait for an obstacle to clear and then had to manuever carefully so as not to lose matter. Right click also switches between lowest rate of time, and middle. Two more controls you'll want to know are...well...restarts. If you find that you've lost too much matter, or another cell has grown absurdly huge, or an attractor (I'll get to that) is collapsing, you'll probably want to hit alt+r. Alt+r is a restart for the level just as it was. HOWEVER, if you find yourself on a level that has a completely unfair start, you can always hit alt+z. Alt+z rebuilds the level, and places things differently. Now, that doesn't work for all levels because some have very specific challenges, but if you seem stuck, give this a shot.
Now that the basics are out of the way, let's get more specific about actual levels. In the beginning you'll play a short tutorial. The tutorial will have one or two levels each for the three types of levels. In Osmos, once you've completed the tutorial you'll be placed at level selection and find three branches coming off of the tutorial levels. There's a survival of the fittest branch where you'll be competing against other kinds of cells to see who can come out on top. These are cool because there's a few different types, and they all move in different ways-one floats around daintly and slowly, one flings itself around wildly, one uses controlled bursts to get where it wants to go, and finally, theres a (boss?) cell which is really smart and manuevers in all the ways you can. Those levels are a bit more action-y than the rest. Lets say you want a more relaxed experience. You'll turn to the purity branch. These levels are a lot calmer. They mostly involve puzzles wherein both light and dark matter cells cover the board, and you'll have to figure out how to survive them bumbping around or boxing you in. Finally, there's the force branch. This one is definitely the most difficult, because, well, it requires the most understanding of forces! These levels are often uncluttered, and fewer cells on the whole, but they present their own dangers in the form of black hole attractors and repulsors and such. All branches will require a good amount of brainpower, but forces will likely require the most.
I'd like to finish by elaborating on the 'ambient puzzle' part. As you know by now, the game is about cells. Well, the backgrounds of the levels are somewhat minimalistic, and sometimes it just reminded me of looking through a microscope at all these little things floating around in their own little microcosmos. The cells are wonderfully designed and have very pretty effects. The backgrounds remind me of other little things in the water, or sometimes space, or some beautiful kaleidoscope. Then there's the music. Wow. There's about an hour and fifteen minutes worth of music, and other than one track that is a bit too energetic for this game, it's a great fit, and really draws you into the experience. It's so good I used it to help me write an essay because it promotes calm and focus so well.
Altogether, this game is a great experience that was lovingly crafted. It's worth the small bit of cash. The only bad thing I can say about it is that maybe the final levels in each branch break the relaxing feel of the game by requiring a lot of quick interactions, and by being especially challenging, but on the otherhand, completing them is really rewarding, and I probably wouldn't enjoy this game as much if it didn't provide some good challenge.
I rate this beauty a 9/10. I believe there is a demo, so if you're still (somehow) second guessing, you can give some levels a go and see how you feel.