Toy Time Galaxy is accessible in the Engine Room with 40 stars.
Star 1: Heavy Metal Mecha-Bowser
Star 2: Mario Meets Mario
Star 3: Bouncing Down Cake Lane
Star 4 (Fast Foe Comet): Fast foes of Toy Time
Star 5 (Purple Comet): Luigi's Purple Coins
This is a difficult star to get. You land in a corner space of a very large area that forms an 8-bit Luigi. Every space of the area is a hazard, excluding the platform you start on. The green spaces started to disappear once you step on them, the yellow spaces begin to rotate when stepped on, and the dark green, swampy area will immediately make you lose a life when touched. Then there's the danger of falling off, of course.
The goal (obviously) is to collect 100 purple coins which are scattered around the area. Once you obtain 100 coins, the star will appear on the platform where you started, so try to move in a circular path. There are a total of 150 coins in the entire area so don't feel bad if you miss a couple, but don't just carelessly miss them. There is no reward for getting all 150 coins, so don't look for one. Occasionally there will be small groups of coins (about 5) in a clump off the border of the area. To get these, a very efficient way is to jump toward them, and quickly spin to move yourself to the cornered square. There will also be large gaps where coins are in a line. Long-jumping is the best way to get these coins or to get to the other side. Lastly, don't worry so much about the clock. You have plenty of time to complete this so stay focused mainly on not falling.
Good luck.