Diamonds is a one-player shareware computer game for the Macintosh written by Oliver Dreer (OPware).
There's not much to the game. There is a bouncing ball, which bounces up and down the screen. You control its sideways motion by pressing the left and right keys. (There is no sideways motion when no key is pressed, and constant speed in the corresponding direction when a key is pressed - no messy acceleration problems in this game.) The ball starts out blue, and while it is blue it can destroy any blue brick on the screen by bouncing off it. There are special, indestructible blocks which will change the colour of the ball - then it can destroy bricks of that colour. Once the ball changes colour once, though, it is impossible to get it back to blue - except by crashing into a 'killerbrick' which causes you to lose one life (but the next life, the ball starts out blue again!). There are coloured keys and locks; the ball must be the same colour as the key to pick it up and must be the same colour as the lock to unlock it. (The ball can only 'hold' one key at a time, but need not remain that colour the whole time to keep it.) After all the coloured bricks are gone, the ball must collect all the 'diamond' blocks, and then the level is completed. There are many levels, like Breakout games.
The goal of the game, of course, is to score as many points as possible before running out of lives (by crashing into killerbricks). As well as points for destroying bricks, picking up keys, and opening locks, there is a time bonus for completing a level quickly.
It is a fast game, and quick reflexes and some planning are required to do well. There are some tricky parts to the game; for example, on one level there is a blue brick between a red colour-changing block and a brown colour-changing block. If you miss the blue brick, you must run into a killerbrick and try again before you can collect the diamonds or finish the level!