Does anyone know how to make a slippery and/or a hazard platform?

I'm assuming you're talking about for the Platformer starter kit? What do you mean by "hazard"?

Slippery: Assuming that you have physics implemented, set friction of the surface really low. If you don't have physics implemented: first, implement physics.

Hazard: Assuming that you have triggers for various surfaces implemented, make a trigger that kills the character. If you don't have triggers implemented: add an Event or similar to the in-game representation of a platform, and when something touches that platform, fire the Event. Use this Event as a trigger.

Thanks jwatte! Any chance physics & triggers are explained in the documentation? Or - does anything in the platform starter kit currently use either that I can learn from?

There's no built-in physics support in the XNA Framework but some libraries have been created. You can check out Ziggy's site for some info.

Will do, thanks Jim!

jwatte:

If you don't have physics implemented: first, implement physics.

Full physics seems like overkill! The Platformer Starter Kit already defines two "drag" constants for when IsOnGround is true and when it is false. The simplest solution here is to replace IsOnGround with an enum thats what surface you are standing on: None, Ground, Slippery. Then choose the correct drag constant from that. See "Apply pseudo-drag horizontally" in the Player.ApplyPhysics method

A "hazard" tile can also be implemented quite simply without a complex trigger system. Define a new tile collision type in the TileCollision enum. In Player.HandleCollisions, simply test against your new collision type inside the "if (depth != Vector2.Zero)" block of code.

When you are learning -- and even when you are a pro -- remember to keep it simple!