As someone who has 'been there, done that' here is a random collection of tips and advice:

• Don't worry about re-inventing wheels---there are never enough wheels and not all of them are round!
• Restrict your input language. In this case I'd suggest PGN (Portable Game Notation) developed by Steven J. Edwards. It is a standard in the chess world and will make you life a lot more fun.
• Resist the notion that you don't need to 'play' the game you are parsing.
• Do the easy stuff first.
• Find someone to ask stupid questions of. PM is good for overall stuff. Idiots like me for chess parsing. Experts like Gmax for the rest.
• Regress. Then do it again! I know of no better task than parsing to implement the pragmatic approach to testing. In a as yet unpublished English to algebraic translator, the testbase includes 3000 games with known results to test against. Every time I think I'm safe---things go south and I'm back to testing. You are never safe---test always!
• Remember, Free Advice---and to paraphrase Curtis Mathis, darn well worth it!