It's really amazing how people keep finding ways to make old hardware do new tricks. Overdrive 2 is my favorite example - it's a Sega Megadrive demo that was released 30 years after the Megadrive launched, but still managed to pull off multiple effects that had never been seen on the system before. It abuses the hardware in such unique ways that no emulator can run it properly.

http://www.pouet.net/prod.php?which=69648 / https://www.youtube.com/watch?v=gWVmPtr9O0g