The PlatformerCharacterBase Entity is a powerful, flexible, and easy-to-use Entity which can be used as a base class for virtually any platformer. The Entity can be downloaded at GlueVault.
This page shows how to perform setup and common tasks with the PlatformerCharacterBase entity.
This page discusses the variables in the Platformer CSV which can be used to modify how the PlatformerCharacterBase entity moves in your game.
If you are making a platformer and using Tiled, then you may be using the TileShapeCollection object. If so, then you can use the TileShapeCollection to perform platformer collision. This page explains how to combine the TileShapeCollection object with the PlatformerCharacterBase.