Last Utopia is a zone in Sonic the Hedgehog Pocket Adventure. This zone is where Sonic must fight the final boss (if you don't have all the Chaos Emeralds), or second to final boss (all Emeralds). It takes place in another rendition of the Death Egg's final boss arena and the music is an 8-bit rendition of the final boss song in Launch Base from Sonic the Hedgehog 3.
The boss is a machine with arms. It also has the Chaos Emerald that Dr Eggman stole from Knuckles in Aquatic Relix Zone. If the player hits the Emerald enough times, it will fall and the player can grab it, adding a new emerald to their collection.
The boss itself has three attacks. It can charge the player, shoot it's arm like a projectile, and spin it's arms around. The most dangerous is when it spins its arms as it covers a greater area.
If the player has all the Chaos Emeralds after defeating the boss, Sonic will transform into Super Sonic and move on to Chaotic Space Zone.