This is an example of one of the glitches in Uber Strike that you can exploit to your advantage.
On the Temple of the Raven map, head to the third floor. You should see a bird, which you need to shoot, at which point it's eyes will light up. You need to be quick now and sprint to the ground floor before shooting the two hanging birds.
Once their eyes also light up, you should appear underwater. Turn around and notice the black box - go inside and you will transport to the secret room!
There are no 'cheats' for Uberstrike. As a Facebook game, if they let you have infinite health or unlock all guns for free, it would make it unbalanced.
There are glitches which help exploit the game's environment, which you can read about elsewhere here. The vast majority of cheat sites or programs to help you in the game are aimed at hacking your computer or account.