We've had Sonic The Hedgehog 2 Dash!, now it's the turn of Crash! And if that sounds confusing, well, it's not. Basically Dash! was the first half of the classic game Sonic 2 for mobile, and Crash! consists of the second half, from the Mystic Cave to the game's final bosses.

If you're wondering why the game has to be split into two, you won't be wondering once you've actually played it.

This is Sonic 2 in all it's glory - with ten multi-layered levels packed with enemies, platforms and pretty backgrounds and its main mammal character (and sidekick Tails) whizzing about the place like a hurricane with blue fur.

With so much packed in, it's already over 1000KB in size. Much bigger and you'd be downloading it in bits for days.

You shouldn't feel short-changed only getting half a game though - not when these ten levels offer far more than your average mobile game. There are rings to collect, hazards to dodge, secret paths to find and boxes of bonus items to smash.

For all the action going on however, Crash! is still a pretty subtle Sonic experience, relying more on observant exploration and a quick eye for spotting hidden traps than simply spinning and bouncing top speed through one screen after another.

Which is just as well because the mobile phone isn't the best format for sheer speed. While the K810i we tested the game on coped admirably with the pace when it picked up, it's still hard to go flat out when you're straining to make out camouflaged hazards.

Jumps that require split-second timing and little inches to the left and right too aren't easy to carry out using a mobile keypad or joystick either.

These multiple routes and hidden paths suit the mobile format far better. It just means you're not actually using Sonic's key skill - his speed - all that often except for trying to gain momentum for a jump or to get up a ramp, which might upset fans slightly.

Speed aside, Crash! has plenty of classic Sonic traits. It has collectable rings, of course - collect 100 for an extra life and collect 100 and pass through any of the level's checkpoints to win the area's Chaos Emerald - and a variety of smashable boxes that reward you with invincibility, top speed and higher jumps, among other things.

It's platforming at its most pure, and really the only thing you can fault Sonic for is being too difficult. Hazards are less easy to see coming on the small screen, and they're more difficult to dodge using a mobile keypad.

Still, the game looks fantastic and features the classic Sonic tunes too. If there's one thing the difficulty level does ensure it's that you won't be spin dashing your way through the whole game very quickly. Although Glu has considerately included a Stage Select option which means that if you get stuck, you can always move on to play another level.

Perhaps unsurprisingly, we're as impressed with Sonic 2 Part 2 as we were with the first half released last year. It might be based on a comparatively old game, but Sonic steamrollers past the majority of platforming competition on mobile without a problem.