Note: My actual playtime is far less than what my displayed playtime is. I accidentally left the game running for two days, so my real playtime is probably around 3-4 hours.
Micron is a puzzle game where the goal is to guide streams of bullets towards the exit by placing pieces that the bullets can bounce off of. It's a very simple concept that is immediately understandable, but it turns out that some very interesting puzzles can be created with it.
A number of obstacles present in the levels create the challenge of the game. Present in every level is a barrier that requires four bullets shots to destroy. These do not make much of a difference in the early levels, but create much of the challenge in the later levels where you are forced to cut off the source of your bullets in order to complete the level.
Gates which are initially closed also appear, and they must be opened by a bullet hitting the correspondingly colored switch. In levels with multiple switches of the same color, bullets must hit the similarly colored switches at the same time in order for the gate to open. Finally, there are barriers which only bullets of the same color can pass through.
Later on in the game, portals which the bullets can travel through are introduced. These are a nice addition that add further complexity to the game, but they also make you wonder whether there is anything else that could be added to the game, as they are the only pieces you can place that aren't ones that the bullets bounce off of. Why not have a "vortex" piece that always makes a bullet turn left or right? How about a "splitter" piece that duplicates a bullet? There is a lot of potential for the concept of this game, and I feel that it is not always realized fully.
The game is also rather short, with only 51 main levels and 12 bonus levels. Most of these are easy and can be solved within a few minutes, although a select few of the later levels are quite difficult. Steam Workshop support helps alleviate this a bit, but currently there are not many user levels available.
Despite this, for $4.99 ($1.49 in the current holiday sale), the game is cheap enough to warrant a purchase for any puzzle game fan interested. The game seems to take a "quality over quantity" approach, and for what the game is, that's perfectly fair.