South Park Tenormans Revenge

The secrets are hidden areas in a level that you access by going through a wall, ceiling or floor. They are hidden well, but there is a diamond in each level that reveals the secret areas by making them sparkle with white stars, making them easier to see.

Here's a video guide for the secret areas, megamen and more than enough Time Cores:

Text guide link HERE

Note: The text guide is written before a major update to the game. Before, you couldn't change characters during a level, so some parts of the text guide might be incorrect. Some locations of the time cores have been changed since then as well.
The text guide is written as the collectables appear in the level, so it should still work.

Thank you McDurbin and BeastlyPappy for your awesome work with the pre-update collectables videos.