Once you beat the Casinopolis action stage with any character, after the cutscene you should see a flying creature coming toward you. That's Cream the Rabbit from Sonic Advance, Sonic Heroes, etc. You can't do anything with Cream or talk to her, she'll just be flying by, and you can't see her again unless you beat Casinopolis again with a different character!
Puzzle Mode:-
Scenario Mode:-
There are a total twelve Game Gear games. They are unlocked as follows:
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0 to 100 Emblems: One Game Gear game for every 20 Emblems.
100 to 130 Emblems: One Game Gear game for every 10 Emblems.
0 to 60 missions: One Game Gear game for every 20 missions.
Tails Adventure is unlocked for getting the other 11 missions.
The games are unlocked in the following order:
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Sonic 1
Sonic Drift 1
Sonic Chaos
Sonic Spinball
The order then varies from here onward for: Sonic Labyrinth, Sonic 2, Dr. Robotnik's Mean Bean Machine, Sonic Triple Trouble, Sonic Drift 2, Tails Skypatrol, Sonic Blast, and Tails Adventure.
To get Tails into Casinopolis before you beat levels one and two, you have to head to the pool near the hotel. When you enter the pool area, head to the southeast corner. Try to run into the corner and you should be stopped by an invisible wall. If you're all the way up against the wall and are facing the corner, you can fly up and head through the wall. From here, fly north, into the direction of the casino area. When you reach it, you can hit the button and enter Casinopolis!