The goal in browser-based sandbox game Tile Factory is to manufacture tiles which meet a specific criterion, and get them from an input point to an output point. This is, of course, not as easy as it sounds.
Tile Factory is a logic/puzzle game of the "progressive complication" variety. That is, you begin with a very simple mechanic, then add another, then another, and so on. In the case of Tile Factory, you are first introduced to conveyers, which simply carry a tile from point "A" to point "B". In order to prevent conveyers from running off the board, you are introduced to blockers. Because simply moving white tiles around is too boring, you are then introduced to sprayers, which add color to tiles. Since sprayers spray more slowly than tiles are produced, you need sensors which can be used to set up timing sequences to be sure everything is in position. Then you add in stencils which protect part of the tiles from the spray, solvent to remove colors, rotators to spin tiles, and so on.
Typical Tile Factory puzzles involve producing a specific pattern on a tile by means of sprayers, stencils, and mixers. It can quickly become a series of extremely complex exercises in logic, requiring--or teaching--an understanding of the basics of circuit design (AND gates, OR gates, and so on). Folks who like this kind of game might also like Manufactoria.
Tile Factory is definitely a game for people who like to work out sequences and steps. It requires no reflexes or timing, and it's not a color or pattern matching game. The process of solving the puzzles is very much the same mental process used in programming. You are, in essence, applying an algorithm to a data element in order to achieve a desired value. There is very little in the way of sound or graphic excitement, and no dancing purple unicorns. I don't mean this as a criticism--indeed, some may find it blissfully free of distractions--but simply as a note to those who conflate "puzzle game" with "PopCap." Tile Factory is also an excellent way to teach some basic programming concepts.