10.4 tiger has classic environment (OS9), means in simple words within tiger sits OS9, but if you have a eMac 700mhz ,800mhz or 1ghz(combo drive only) you even can boot direct into OS9 , for the later 1.25, 1.42 there is the classic environment
you can play all the great old os9 games , so dont delete it

, OS9 is a great operating system ,and classic is a great feature and so much fun
and even some might say they need the latest version of an app , but in my opinion for home use you can still use a older version without any problem really and you get a taste of how working on a Mac was pre OSX
if you need some old games to try and enjoy

look here they are all abandonware means nobody cares if you download and use them
http://www.macintoshgarden.org/games
there are also some great apps (programs ) too and they still work
http://www.macintoshgarden.org/apps
just give OS9 a chance you will not regret it