These are legitimate games developed or licensed by Square Enix specifically for mobile devices. You can find these on the Google Play Store.
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The APK (Android Package Kit) is the app itself (roughly 30-50 MB). The OBB (Opaque Binary Blob) is the data file containing the game's assetsāmaps, character models, voice lines, and textures (roughly 2.4 GB). You need both. Tomb Raider Game Download For Android Apk And Obb