The World Entrance is the hub world of Knuckles' Chaotix. It is also where the game's final showdown takes place.
The World Entrance is the main area of Newtrogic High Zone. After the Introduction place, the player must choose a main character besides Heavy and Bomb, who are only combi partners (unless they are picked through the hidden stage select, including "Wechnia"). The player can exit to the title screen on the left, but going right proceeds to three particular rooms: the Attraction Information where the levels' progress is shown, the Combi Catcher, and the Stage Select room. Upon entering the final room, the machine activates a roulette for each attraction. Touching the star marker in the middle will stop the selector, landing it on a place. The characters will then be launched to their destination towards the right.
After five levels of each place are cleared, Metal Sonic will appear and take over the Stage Select machine. The player must land the marker on the X for the machine to take damage, or else it attack. After it has sustained enough damage and all five boxes are eliminated, Metal Sonic will fly to the right as the player characters fall to a hidden room. At an unseen location to the right (or the room where the player characters fought the final boss), Metal Sonic approaches Dr. Robotnik, who tampers with the Special Ring and takes off with it and Metal Sonic. Meanwhile, the two heroes land in a room with a monstrous mech which must be defeated in phases. After its defeat, the room will explode and twirl in a flash. If the player collected all the Chaos Rings, they will show up and appear to teleport all the characters to safety (with Heavy and Bomb replaced with Sonic and Tails on the Tornado). If not, then the monster will be revealed to not be entirely defeated and go on to wreak havoc.