Square Logic is a game in which you try to solve a grid of numbers, given a set of rules. Each row, vertical and horizontal, contain only 1 of every number from 1 to whatever is needed to fill the grid. (If the grid is 4x4, then numbers 1 through 4 will be in each row.) You Sudoku fans might recognize the basic concept of the game, but Square Logic takes it all a step farther.
Unlike in Sudoku, you are not given very many numbers, and there isn't any need to guess. Instead, the grid is covered in groups of blocks, each with a mathmatical rule of some sort. For example, one of the first rules introduced is the addition cube, which means every number in that group adds up to the given total. For example, a grid of 3 squares that add up to 5 on a 4x4 puzzle means the numbers in that group can only be the following combinations: 2 + 2 + 1, or 1 + 3 + 1.
Of course, just knowing those three numbers are in the group doesn't give the order or arrangement of the numbers, which is where the other Sudoku rules come into play, as well as the other groups on the board.
Don't let this math scare you off, because Square Logic will actually do it all for you. Hold your mouse over any group you know the rules for, and the game will show you all the possible number combinations for solving that group. If you eliminate numbers through solving others in the row or through educated guesses, Square Logic will update this list by crossing off the combinations that are physically impossible to put into the group. The game will even automatically eliminate numbers when you solve one in a row.
The real reason Square Logic is so good however is the complete lack of guessing. Every single puzzle in the entire game is solvable through pure step by step logic. In fact, the hint system of the game will tell you the next step it would take to solve the puzzle, instead of simply giving you a number like most Sudoku games will resort to doing. The game itself understands the steps needed to solve puzzles, and will happily point out a row to you saying "try logically eliminating some more numbers from here", or "This group can only be solved by one of it's equation answers". This feature makes the hint button much less of a "cheat", and more of a simple nudge in the right direction for solving the puzzle logically.
As for length, each of the game's areas contain 12 practice puzzles and then a challenge puzzle(which you can simply challenge at any time even if you didn't do the practice puzzles once you get to the section). Solve the challenge puzzle and the game will unlock two things. First, you'll get access to the next area, with a new set of logical rules. And second, you'll unlock every single "solvable without guessing" puzzle that can possibly be generated using that area's rules. In many cases, this results in unlocking over 100 to 400 more puzzles of that type, to be solved whenever you feel like it. When you consider a lot of these puzzles will take an average of 20-40 minutes to solve, this game is well worth your money.
The simple beauty of Square Logic's interface and smartness, combined with the complete lack of guessing needed to solve it's puzzles, leave you with a very solid game that is fun to play, and gives your logic circuits a good workout while avoiding any of the pitfalls like timers, luck based elements, or complicated controls that so many other casual "puzzle" games fail to avoid. I can't recommend it enough, and for the price, it's practically a steal. This is a game that can easily replace your daily "Sudoku" puzzle in the newspaper for many years to come.
Get it straight from Steam here. It's probably one of the few games I have played that I can safely say everyone, no matter their video game background, will enjoy to the fullest, and for only $10 USD for a game that will probably last a lifetime, there's literally no reason not to own it: