Here comes some more easy to answer questions that don't really need their own thread.

1) While creating a multiplayer game, I know I can use xna for part of it. But for usernames and information like that, would I need to use SQL and set up a server to host games?

2) Imagine you're looking at stairs from the side:

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In order to make my player move up the stairs without jumping, would I need to implement octrees into my cube creation?

3)Will HLSL be able to handle effects like creating a beam of light shining onto a player's position from a dark sky, or sparks like the wisps in Warcraft 3?

4)My AI in my game will be simple, much like League of Legends. You will be able to set a spawn point and with a click of a button you can send your troops to attack an enemy wall or tower. If your troops come into range of any other troops or the enemy's structures, they attack. What kind of AI scripting would I need for something simple like this?

Thanks again in advance :)

The flecks of light would probably be a mixture of a particle engine and several shaders combining effects over them.

1) You can use any kind of database. The most extreme way of course would be to create an SQL Server. For our game we are using SQLite, but it's a singleplayer game.

I would recommend to look into NoSQL like Mongo or CouchDB.

2) Check out BEPUPhysics, there is an example for this. They solve the problem for you. :)

3)Not sure how to solve this one, you can probably solve it with a conical mesh rendered with additive blending, but I don't know. There are so many ways to do it.

4)First of all the AI of LoL is not simple :). I would recommend that you check out CAINav http://www.critterai.org/cainav/home, it's based on the recast library.

And for steering check out SharpSteer http://sharpsteer.codeplex.com/.

1. For the Xbox, XNA networking is the only thing you can use. On the PC, that isn't available to you, so you have to use something else. On the phone, I forget...

2. Octrees are a performance optimization, and as such are kind of orthogonal to your problem here.