Not safe. While it won’t download malware on your device, the entire site is a bait for a phishing network.
When you select a game to download, the site will display a fake “downloading and installing” animation but it’s not actually installing anything. When the loading bar reaches 100%, it will say you need to “complete at least 2 offers” to unlock the game. The “offers” require you to enter personal details and sign up for paid services.
It might not all fit anyway, glass protectors are quite thick and if you put one on the back of a phone, it will probably no longer fit properly inside a case.