Indoor Heli Sim 3D Free, developed by iDL Corporation, is a simulator that allows users to control small RC helicopters, including single-rotor and quad-rotor helis. This game is specifically designed for Android users, and requires Android 3.1 or higher to play.

One of the standout features of Indoor Heli Sim 3D Free is the ability to use a USB game pad, such as the USB FMS controller, via a USB host cable. This adds an extra level of realism to the game, allowing users to truly feel like they are controlling a real RC helicopter. The simulator also offers a variety of different environments to fly in, including a living room, a gymnasium, and an outdoor park.

Overall, Indoor Heli Sim 3D Free is a great option for RC helicopter enthusiasts who want to practice their skills or simply enjoy flying without having to worry about damaging their real-life helis. And with the added option of using a USB game pad, the experience is even more immersive.