I'm making this thread because SpaceChem is an incredibly well designed game, but it is easily looked over: it looks boring in a screen shot, boring in a video, and boring in a two sentence description. It's a game about chemical engineering where the only graphics are chemical diagrams made with lines and circles. Most all the traditional methods for sparking people's interest in a game fail for SpaceChem (except it is well received by critics, with an 84 on metacritic).
HOWEVER, remember that Tetris also probably looked and sounded pretty boring too, when you first saw it. SpaceChem is a puzzle game as well, and a rather brilliant puzzle game at that. Though I mention Tetris, SpaceChem plays nothing like that. It has more in common with puzzle games like The Incredible Machine, though it's still different from that. It is SpaceChem. It is it's own thing. SpaceChem is a good game for people that like making machines, that like engineering, that like visuo-spatial puzzles, and that like solving problems that have more than one right answer (allowing your solutions to be as elegant or over-complicated as you want them to be). The basic gameplay is about designing a machine that takes basic chemical elements for input, runs them through a mechanical loop wherein a number of machines create and break chemical bonds to form molecules, and then it drops those molecules off in output, and cycles back to the input. Your machine will have to be able to run in multiple cycles without creating a collision.
SpaceChem is not for everyone. It is rather plain looking. Though it does attempt to graft a framestory to provide a rationale for the work you're doing, the gameplay is entirely about chemistry puzzles. The game is also exceptionally intellectually challenging. You don't need a background in Chemistry or anything like that, but you will need to be able to visualize in your mind how objects move, rotate, and react in a sequence. It challenges your visuo-spatial abilities quite well in just the first set of tutorial levels, and then proceeds to brain melting difficulty soon after that. HOWEVER, if this is your kind of game, it will VERY MUCH be your kidn of game. The gameplay is deep, and it's basic logic is beautiful. It takes a lot of work to find the right solution to creating any given molecule, but it is exceptionally rewarding to finally figure one out and then to watch the animated cycle play out perfectly. It's also a game that rewards creative problem solving. Every puzzle has multiple possible solutions. The game does track how many pieces of equipment you used though, so you can compete against yourself or the online leaderboards to find the simplest, most elegant solution to any problem that requires the fewest amount of steps.
There is a demo if you aren't sure about putting money down. Also, the mobile version is on sale for $1.99 for the next few days:http://spacechemthegame.com/