Looking for a chess engine...

Greetings first I'd like to thank you for reading my post.  I joined Chess.com a few months ago and have since been bitten by the chess bug.   My play has improved greatly but that has recently plateaued.  I am looking for Mac OSX compatible software that could help me with game analysis I have downloaded quite a few programs from Chess.com but none seem able to help me with analyzing my games or give any alt moves when I make a mistake.  Any suggestions?

Thanks for the suggestions but maybe I should have been more clear on what I am having trouble with.  I would like to get something that tells me when I make a mistake in a game what lines exploit that mistake and what move I should have made.  I have downloaded HIARCS lite and Glaurung 2.2 but still can't find anything that can help me with my analyzing my games unless I set a position and have the cpu play my side and I play my opponents moves but It really isn't helping too much and I am not familiar enough with my opponents positions to offer much of a threat to these chess cpus.  Is it just a database that I need to do this? How can I pair a database with Glaurung 2.2? or Do I just need to open the database and use it separately from the chess engine?

I'd recommend Glaurung 2.2. 

http://www.glaurungchess.com/

I run HIARCS 12 lite, the free version of HIARCS 12.

HIARCS now has a standard UCI, so it can run with lots of GUI programs, Sigma Chess being one of the best, but you need to purchace a HIARCS registration to have the full power engine. HIARCS lite is weaker, although still around 2500, according to their website.

i think fruit/toga is one of strongest free engines on mac

thanks, eaglex, I didn't realize fruit was availible for Mac. I'm gonna take a look at that.

Ok that is easy. Get Sigma Chess 6.1

Install the Glaurung 2.2 engine

Then insert an entire game and go to Analyze game. 

Wow Chess.com has another feature that's truly exclusive?  Does anyone know of any program that's even close to Chess.com when it comes to helping players develop a better gameplay?

Not too sure if Crafty works on Macs, but you can get the program here:

http://www.craftychess.com/

After that get winboard from http://www.gnu.org/software/xboard/

Install winboard and it should work

ExaChess will do what you're looking for, and if you get Fruit you can use that as an alternative to the engines that come with ExaChess.

Note that ExaChess is intended to be a chess database/toolkit.  The free version has a cap of less than 300 games per database, and a few other limitations, but the Annotate feature (what you're talking about) is totally functional, even in the free version.

If you're willing to pay, the Shredder 12 package also provides game analysis.  (But for what it's worth, I prefer the annotation style in ExaChess.)  Good luck!

Listen to this guy. In Sigma Chess, load up the game, select the move you want to start analysing from (the first, generally), and Analyse game is under the "Analyse" (fancy that...), the shortcut is ctrl-cmd-a.