Secret rooms in krtd

Answer from: EmeraldDragon
In level 1-2, go to the room with the needle ability. Go to the Maximun Tomato on the right of the wall. Fly up to the left side of the top and you'll see a black spot in the bush. Inside you will see an Invincibility Candy. For level 1-4, go to the end of the first room, but skip the door and go to further right. Then, go back to the place where you run past the falling rocks, you will see a hidden door in a secret place, inside is the HAL secret. In stage 5-5, climb the tower, but do not go in the door. Instead, fly higher and find a barred door, go in. Everything is backwards and the boss fighting room is smaller and more challenging. Also, there are different ways to get the Energy Spheres. In level 6-5, go to the room after the first crushing stage. At the end of that room, you will see a bunch of Halcandran Waddle Dees. Go up the conveyor belts and to the dead end. You will see a hole in the net-like background which is the secret door, the HAL secret is found. In 7-3, at the goal door, instead of going in, there is a meteor right above, enter the meteor. You can skydive and follow the path of star coins and food. Is there any others?

Answer from: Tip Ninja
I said that I already know those locations, but thanks for answering.

Answer from: kirby
There is also one in 3-3 in the seaweed on the other side of the brick with the marked door that has a invincibility candy inside. the secret door leads to a energy sphere.