A great title in the Sonic library, and worthy of the hedgehog's glory days.
You'll guide our spiky hero through a variety of colourful and fast paced levels facing off against decent selection of boss robots controlled by Dr. Robotnik. The levels are fun, and have secret areas to boot. The ease of the game comes mostly from how readily available rings are. Collect 100 rings in a stage and get transported to a bonus level were you can easily rack up a half dozen bonus lives. Of course if you stop to get all the extra lives you can before time runs out, you'll miss out on the chaos emerald at the end of the level which has it's own repercussions.
You can also play as Tails, which does make it harder to get these bonus lives, but he comes pre-equipped with extra continues in hand.
The final level does ramp up the difficulty, and you won't be able to see the 'real' ending unless you collected all of the chaos emeralds on you're way there. Of course, nothing indicates that you needed to do this, so for the longest time I was always very confused by the end.
Although it doesn't take long to get to the end of the game, it's the perfect length for a hand-held title, especially since the Game Gear was famous for draining battery power.
All-in-all it's a great title for the Game Gear, and a great Sonic title in general.