Move the extracted folder to this path: sdcard/Android/obb/ . The final path should be sdcard/Android/obb/com.madfingergames.shadowgun .
RAM: 1GB minimum, though 2GB is recommended for fluid frame rates during heavy combat.
A2: Shadowgun v163 was designed for much older Android devices (v2.2+), so it's highly likely that your modern Android smartphone or tablet will have more than enough power to run it. However, some newer devices might experience compatibility issues due to differences in screen resolution or processor architecture.