The idea behind the game is loosely based on X-ray diffraction of crystals. You have a grid in the centre, into which the computer has placed 4 or 5 atoms. You are trying to work out where the atoms are, which you do by sending rays into the grid and seeing where they come out. The arrow keys move a cursor around the grid, allowing you to place your guesses as to where the atoms are. Pressing G then asks the computer to mark your guess. I completely forget the scoring system, I'm afraid, but basically you get penalized for wrong guesses and score less the more rays you have sent in. The letter keys (J and K, if I remember correctly - I don't have the game in front of me) move a marker around the edge; pressing return then sends in a ray. When you send in a ray, it interacts with the atoms in there. There are three things that can happen: - the ray is absorbed by an atom - the ray is reflected and comes back out where it went in - the ray comes out somewhere else. An icon appears where you sent the ray in. The first two cases have standard icons, while in the third case two new icons appear, one where it went in and another where it comes out (the logic is symmetrical, so if you had sent the ray in from there it would have come out here). Each ray that emerges elsewhere gets a different icon. Rays go in a straight line until they approach an atom. When they do, they can be reflected or absorbed. * A ray that reaches an atom head-on is absorbed. This includes the case where an atom is on the edge of the grid and the ray is sent straight into it. [In the following, == or ! show the path of the ray, A is an atom, and R is where the ray was sent in from. X shows a ray being absorbed.] | | | | | --+-------+-------+-- |-------+-- | | | | | ============X A | R ==X A | | | | | | --+-------+-------+-- |-------+-- | | | | | * A ray that meets a single atom corner-on is reflected at right angles. It then continues on its way: it might be reflected again, absorbed, or eventually emerge: | | ! | | --+-------+---!---+-------+-- | | ! | | | | ! | | | | ! | | --+-------+---!---+-------+-- | | ! | | ==============/ | | | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | | | | | --+-------+-------+-------+-- | | | | | A | | | | | | | --+-------+-------+-------+-- | | | | | | /============== | | ! | | --+-------+---!---+-------+-- | | ! | | ==============/ | | | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | | | | | --+-------+-------+-------+-- | | | | | | A | | | | X | | --+-------+---!---+-------+-- | | ! | | | | ! | | | | ! | | --+-------+---!---+-------+-- | | ! | | ==============/ | | | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | * A ray that tries to go between two atoms is reflected back the way it came. A ray that goes in one row or column away from an atom on the edge (and so ought to be reflected through a right-angle before it even enters the grid) is also reflected back the way it came. | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | ==============| | | | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | | | |-------+-- | | R ==| | | | |-------+-- | | | A | | | |-------+-- | | | | | | --+-------+-------+-------+-- | | | | | A | | A | | | | | --+-------+-------+-------+-- | | | | | | _ | | | | ! | | --+-------+---!---+-------+-- | | ! | | ==============/ | | | | | | --+-------+-------+-------+-- | | | | | | | A | | | | | --+-------+-------+-------+-- | | | | Finally, here's an example grid with the complete set of ray behaviours marked out (X for absorbed, R for reflected, digits for in-out pairs). As a bonus, each X is labelled with which atom (A to D) absorbed it (obviously the real game doesn't do that). 0 R XA R XA XC 1 2 +---+---+---+---+---+---+---+---+ XA | | | A | | | | | | XA +---+---+---+---+---+---+---+---+ XB | | | | | | | | | 3 +---+---+---+---+---+---+---+---+ 0 | | | | | | | | | 1 +---+---+---+---+---+---+---+---+ XB | | B | | | | C | | | XC +---+---+---+---+---+---+---+---+ 7 | | | | | | | | | R +---+---+---+---+---+---+---+---+ XD | | | | | | D | | | XD +---+---+---+---+---+---+---+---+ 6 | | | | | | | | | 4 +---+---+---+---+---+---+---+---+ 5 | | | | | | | | | 5 +---+---+---+---+---+---+---+---+ 7 XB R 3 6 XD 4 2