The CD-ROM magazine Inside Mac Games maintains a list of forthcoming Mac 
games; if you're not a subscriber, you can download the latest demo issue 
from <ftp://mirrors.aol.com/pub/info-mac/per/img/> or from their web
site at <http://www.imgmagazine.com>.

There is a list of forthcoming game releases available from Computer
Express at <ftp://ftp.std.com/vendors/COMPUTER_EXPRESS/>.
This list has expected shipping dates for both IBM and Mac games.

Games almost invariably ship later than the expected shipping date;
to approximate the actual date of release, double the time between
now and the listed date, then add an extra month for good luck.