alt Hacker NewsRoku remotes are sophisticated devices. There are many models, so features vary, but among the possible features are 3.5mm audio output, Bluetooth audio, voice command input, Wi-Fi, infrared, battery charger and other things. Clearly a substantial MCU is present and thus, an RTOS.
Pretty sure they don't have gyroscopes and accelerometers anymore, but they did early on. It was basically a Wii Mote and I played a ton of Angry Birds on my TV.