You can try http://flashgamedistribution.com/ for .swf files. These games will not be modified or branded to your liking, nor can they be reuploaded to other sites under your name. However,they can be used if you have a gaming site.
You can try this http://www.flash-game.net/ Or my favorite is Yeti games https://www.yetisports.org/ site is a bit slow to load but you will like it....