This mod for Harry's Removed Crosshairs A20 will add an aim down crosshair to the game when you are aiming at a target. It only affects guns, not bows. It also removes the crosshairs when you are shooting down at the ground, which is a bug that I have encountered.

It also includes a number of sound effects to enhance the experience of the game. It includes a level up sound, assault rifle reload, shotgun reload, assault rifle fire, shotgun fire, and a number of vehicle sounds.

This is a very easy to use mod, just download it from the Google Play Store, open the game, and you're done.