In the main page there were maps for each level of the X-Mas edition of Happyland Adventures.
Here are maps for other levels of Happyland. Unfortunately, these are only the maps (no walkthrough, tips, or minimaps):


Happyland Adventures, The Original Version:
Welcome to Happyland (First Level)
Happyland 1
Happyland 2
Happyland 3
Crazy Caverns 1
Crazy Caverns 2
Crazy Caverns 3


The Bonus Levels:

X-Mas Edition Original Version
Bonus Room 1
Bonus Room 2
Bonus Room 3
Bonus Room 4

Secret Room


Bonus Room 1
Bonus Room 2
Bonus Room 3
Bonus Room 4

Secret Room


Let me remind you that to get to a bonus level you need to save all of the Happylanders (not just enough to open the doors, but all of them), and then the enemies will turn into coins that you should collect. If you collect all the coins you will enter a bonus room at the end of the level.
If you collect enough happylanders to open the doors, but you can't find all of the other happylanders, it's enough to get just one happylander and go with him to the exit. If you take a happylander with you he will thank you and send you to a secret room.


Rolling Hills Levels:
Rolling Hills 1
Rolling Hills 2
Rolling Hills 3

The Rolling Hills level set is a part of the example maps in Happyland v1.3.
When you play these maps, it's important to remember the trick in Happyland that when you roll down a hill and gain acceleration you can make very big jumps, and this way get to places you can't reach with a normal jump.