CharacterController2D is similar to the built-in Unity CharacterController component. It has a similar API (mainly a move method that takes a delta movement) and provides a firm base with which to make a super solid controller using Unity's 2D system.
A simple demo scene is included along with a few Spelunky sprites (which obviously should not be used in your game!). An overview video showing how to get started is available on the prime31studios YouTube channel here.
The included demo scene is minimal to keep things as simple as possible. It has very basic input detection (using the arrow keys to move, jump and fall through one way platforms) and a simple character sprite/Animator setup. This should be simple enough for anyone with a rudimentry knowledge of Unity to read through and understand.
Setup is pretty simple: drag the CharacterController2D onto your player/enemy GameObject and set the platformMask in the inspector to contain any layers that you want the player to collide with. If you will be using one way platforms, you can set the oneWayPlatformMask as well. Note that one way platforms should be EdgeCollider2Ds. ProTip: make sure your player is on a separate layer than your platforms so that she doesn't try to collide with herself! You will also want to make sure you BoxCollider2D is centered and has a zero horizontal offset. Flipping requires setting the scale.x to -1 so a horizontal offset other than zero will result in the collider jumping around.
You can then tweak the totalHorizontalRays and totalVerticalRays to your liking. When in the editor rays will be drawn with Debug.DrawRay so that you can make sure the ray resolution is appropriate for your smallest platform size. To turn off ray debugging just comment out the #define DEBUG_CC2D_RAYS line at the top of the CharacterController2D.cs file.
To move the player around just call move and provide it a delta movement (the physical distance the player should move this frame). You can subscribe to the onControllerCollidedEvent to be notified of all collisions if you need them.
In order to be able to receive trigger events (onTriggerEnter/Stay/Exit) the CharacterController2D needs to be told which layers it should interact with. Select the layers that should fire trigger events via the triggerMask field in the inspector.
Attribution-NonCommercial-ShareAlike 3.0 Unported with simple explanation. You are free to use the CharacterController2D in any and all games that you make. You cannot sell the CharacterController2D directly or as part of a larger game asset.