F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.
itch.io - An online game marketplace and community.
Aptoide - Aptoide is a third party replacement for the traditional Google Play Store.
GOG.com - DRM-free game store, selling both new and old titles. No clients required.
APK Pure - Download apk for Android with APKPure APK downloader. NoAds, Faster apk downloads and apk file update speed. Best of all, it's free
Ubisoft Club - Ubisoft Club app enables you to get updates about your favorite games timely.