One of the best games I've ever played.
+ This game is one of a kind and it can't really be compared to anything else. It is entirely rule based, and while the rules are simple to learn the outcomes of each puzzle prove challenging to accomplish.
The goal for each basic level is to input chemical elements, manipulate them in a certain way on the board, and then output the new desired chemical element. Each level has a 10 square by 8 square board. There are two possible places where chemicals can be input into the board and two possible places where they can be output (though not every level makes use of all of these). Sometimes one input location can produce a variety of chemicals, so you aren't guaranteed to know which element it will make (but you are still given the probability of each being input).
You also have two "waldos" -- red and blue. These are basically cursors which follow paths that you create on the board. On each path you must place certain instructions which will tell the waldos what to do. Some of these instructions including inputting an element, outputting an element, grabbing an element, bonding an element, rotating an element, and synchronizing the waldos so that they will only continue when both of them have crossed a sync. Later in the game there are more sophisticated commands like fusing, switches, and checking to see if a certain element is at a location.
It may be hard to understand what all this means, but it's easier to think of an example. Say there is an input element at the top left of the board which always produces Hydrogen, and the input element at the bottom left of the board which always produces Oxygen. The desired element at the top right of the board is water (two hydrogen and one oxygen bonded into a single element). You will then have to build a path on the board and place commands that will input these elements, bond them, and output them. But you can't just do it once and be done. You will have to build a machine that will be able to reproduce this a number of times without having an error.
It can be confusing to learn at first, but once you understand the logic then it becomes extremely hard to put down. In fact this game really resembles programming logic because of the simple, structured rules that you must work with. Take inputs and design a path with rules that manipulate them to the desired output. That's what's going on. So if you love logic and you have a programmer's mind then you should be able to grasp it quickly.
The game does a good job of progression, too, and continuously adds new challenges just when you think you've learned it all. Once you've moved beyond one-board levels then they introduce levels where you have multiple boards (or "reactors"). So it's not just working with two inputs and two outputs, you must pipe together a number of these and make sure everything is in full synchronization. And there are even boss battles which are special, unique, and even more challenging.
I cannot remember the last time that I was completely blown away with how good a game was. And this game is really special. I've never played anything like it before, and it really catered to my logic/programming/puzzle mind. The rules are structured perfectly so there is little confusion to what they do. And there are many, many ways to solve each puzzle so you are free to build each board however you can.
The one minor thing that detracts from this game and prevents it from being a perfect 10? The game can be VERY challenging. Near the end of the game the puzzles are extremely difficult and it will take hours just to analyze the situation, try different results, make some changes, and keep trying to get the answer. I like a challenge, and it was nice because after I solved these hard puzzles I felt an incredible sense of pride. But I will advise that not everybody will make it to the end. If you are stuck and just can't think of how to solve the puzzle then there really isn't much help that the game provides. You either figure it out or you are stuck and can't progress further. In fact, I got side tracked and never managed to finish the final levels (but I do hope I get a chance to eventually).
Still, this game is amazing and the gameplay is extremely solid, well-grounded, and hard to find faults with.
Story/Presentation: 5/5
+ There is a story in this game! I wasn't expecting it, but it really blew me away. The story is given as separate screens of text after beating certain levels. And the writing is actually very good. It feels like a professional author wrote this short story and it fits perfectly with the game (in fact, it kind of feels like a few George RR Martin short stories I've read).
Once you read the story you begin to see that the puzzles aren't just there for the sake of a game. It actually feels like you are the main character in the story and you are experiencing everything. This synchronization between story and play is rarely found in a game, but SpaceChem does it perfectly and really fuses them together.
The writing is spectacular, mysterious, and compelling, and it really does make you want to keep playing so that you find out what is going to happen. Again, I haven't played the very final levels so I think I haven't read about two pages which conclude the story. But up until then everything has been incredible and way beyond what I was expecting. I'm hesitant to judge the story without completing it, but it really does hold a lot of merit up until this point.
Graphics: 5/5
+ The graphics are simple yet beautiful. Everything is clearly displayed on the screen and there is rarely any confusion with what is going on. There are a few special effects that make things a little nicer, too. The bosses and environments look hand-drawn by a professional artist and they really are gorgeous to look at.
But I think the real key to the success of the graphics is that they are not in-your-face and obnoxious. Everything is crisp and clean and viewable. The levels can get confusion and complex, but because of the graphics are so carefully chosen everything is still viewable and manageable to work with. It is really impressive what they managed to accomplish.
Value: 5/5
+ Absolutely buy this game. There is no question about it. It's $15 and probably the best value I have ever spent for a game. So far I've played the game for 30 hours but I still have a few levels to go back and play in order to completely beat the game. And once you beat the game there are still special challenge maps that you can play. Also, beating a level doesn't mean you are done with the level. Each level rates you on how many cycles it took to beat (how fast your solution takes to finish) and how many commands you used. You can always go back and try to optimize each solution and lower those numbers. Usually a solution is mutually exclusive and will either have low cycles or low commands, but it's fun to go back and compare yourself with the graph of everyone else.
I cannot stress enough how impressed I was with this game. The rules and logic are flawless and the gameplay is free and open for you to experiment and solve puzzles. The story is wonderfully written and really engaging. The graphics are beautiful and fitting. The value is spot-on.
To be fair, this game isn't for everyone though. It involves a lot of heavy thinking and experimenting. But if you love puzzles, logic, and/or programming then there is no reason you should skip this game. Heck, even if you don't then you should still try it because you might be surprised with how addicting it can be. It is a blast and entirely rewarding every minute I played it. Buy this game now.