System 7 won’t run on any model of iBook, the earliest ones shipped with MacOS 8.6. Your best bet for an operating system is probably MacOS 9. Watch out on the 2002 and later models, as they may not work with the standard MacOS 9 installer and instead need a system specific version.
That being said, the mid 90s games you are thinking of should run just fine on any model iBook you get a hold of. Macintoshgarden.org is a great place to find software from that era. Hope this helps.