Sonic 3 (Mega Drive/Genesis)
Here’s where it starts to go wrong. Only starts, mind – Sonic still rocked at this point. The emphasis now is on the spectacle rather than finely balanced gameplay. Worryingly, there's another character (Knuckles), who isn't playable yet, but brings the main character roster to three. Four if you count Robotnik. Five with Amy from Sonic CD. Six if you count Metal Sonic. See where this is going?

However, two standout levels are worth the entry fee alone - the Ice Cap zone with its multi-layered backgrounds, beautiful cavern and goosebump-inducing music, and Hydrocity with the game's fastest, smoothest moments and most memorable imagery.

Above: The Hydrocity zone is one of Sonic's finest hours. He looks pleased

Looking at the game today, the rest of the experience is patchy. The special stages were another graphical leap over those of Sonic 2, now with a convincing 3D effect on a curved scrolling floor. But they weren't much fun and, in the end, the huge gold rings that led to them became something to avoid instead of seek out. That is, at least if you were just playing for fun, not completion.

Also new were themed shields that allowed you to attract rings breathe underwater or become a fireball. These were fun and did add to the experience. It also helps to be able to save your game – a feature now essential given the game's increased size. Set-pieces were better too, such as the snowboard introduction to Ice Cap zone (pictured here), which was resurrected for Sonic Adventure.

Like Sonic 2, Tails can be controlled by the second joypad, although now he has more purpose, as he can lift Sonic for a limited time and fly him to safety or a previously unreachable ledge and to new routes only available this way.

When it's at its best, Sonic 3 is one of the greatest platformers ever made. But some levels are dull, overly long, or just confusing to look at, such as Carnival Night. Still, it's the most polished 2D Sonic in terms of graphics and sound, and certainly still worth a look. But, unlike its predecessors, it's not quite essential.