4 Foot-tap (Sonic The Hedgehog 1991)
We almost included the 'eeeerk' stopping animation as one of the best Sonic moments, but it's not quite as iconic as the foot tap. Sure, it's been copied a thousand times, but the first time we saw it was a revelation. Breaking the fourth wall and all that. Sonic turns to the camera, eyeballs you and then starts tapping his foot impatiently. Infinitely more appealing than a voiced character saying 'better get going'.

3 Water Slide (Sonic the Hedgehog/Sonic Adventure)
Let's face it – there aren't that many surprises you can pull in a 2D game. No sudden into-the-screen shenanigans on a Mega Drive. But the first time we stepped onto that slippery slope, we gasped in awe. A change of pace, the feeling of being out of control – just like the best rollercoasters. And then it showed up again in 3D in Sonic Adventure and was even more exhilarating!

Above: Control's taken away... but you can jump to find some secrets

2 The Killer Whale (Sonic Adventure, 1999)
This almost stole the top spot in this list. Why? It's almost a decade old but still looks amazing. And the re-appearance in the 360/PS3 game was nowhere near as impressive. Splintered boardwalk, razor-sharp teeth, crashing waves… awesome.

 
Above: If you get killed in this bit, consider yourself beyond help