AwareTek’s Chess Database is available on the Apple Macintosh App Store and is a PGN file reader, database and analysis program. You can download all the great grandmasters’ games from sites like http://www.pgnmentor.com/files.html and replay them one move at time, with real time analysis and suggestions. You can also play the game out from any position in the game from either the white side or the black side.
You can also input and store your own games and then play them to get analysis on good moves versus bad and etc., including a real time score that shows which side has the advantage at any given time. A positive score means white has the advantage and a negative score means black has the advantage. An advantage of +1.0 means white has approximately a one pawn advantage.
The PGN file format is a standard and much information is available on the web. You will be surprised how much you can improve your game by using these tools. The functionality of Awaretek’s Chess Database costs hundreds of dollars from other sources and for other platforms. Chess Database for Mac costs $9.99 and is selling very well.