Xbox speeds up research results

There is an interesting article on the BBC today about some researchers using the Xbox GPU for parallel processing.

This would actually be fairly easy to do with XNA, though I would be really interested in seeing the types of HLSL they write for the algorithms. The only difficulty, as I see it, is that XNA doesn’t have a generalized API for data transfer to a server. The networking API’s allow you to communicate between other clients in multi-player games but they do not let you upload results to a server. They might let you upload top scores and a few other minimal stats but certainly not the large datasets these researchers are looking for. It would be really cool if the XNA team created a complimentary server client that would allow 3rd party indie game developers to create server software to enable this type of application as well as ones that might involve persistent worlds and things like that.

I would be very interested in something like that.

Zune games with XNA

The latest version of XNA comes with support for creating games for the Zune. I’m pretty excited about this and have embarked on an open source game with three coworkers called ZuDoKu. It will be a collaborative Sudoku variant for the zune.

I figured that in order to get this going I was going to have to update my Zune software finally. I haven’t been able to update it since I first got it, it’s not that I didn’t want to but it was just bombing out during the update process every time. Well I spent two hours of my friday night trying to fix it and finally was able to! It was choking when trying to access certain registry keys and when trying to unregister an assembly called Flash9b.ocx. Well both problems were eventually resolved by navigating to the registry keys in question and giving myself the correct permissions to manually delete the problematic keys.

It seems that Flash v9b was actually setting the “Everyone” user to be denied to delete some keys and their uninstallation process was not cleaning these keys up properly, which in turn was causing the Zune update software to choke. Well, after manually deleting all of the Flash related keys in HKLM\CLSID (after uninstalling flash of course) I got the update to finally work! I’m pretty excited… now off to game programming!

Shawn Hargreaves at the Twin Cities XNA User Group

This May 15th, the Twin Cities XNA User Group is pulling out all the stops to bring you a Shawn Hargreaves (Microsoft, XNA Team) Double Feature! Shawn is flying in from Redmond for one night and while we have him here, he’ll be answering YOUR questions and presenting on the following topics:

1.) Defeating the Network Game Gremlins and

2.) Understanding Shaders.

For more information and to register, please visit

Meetings are held at Magenic (4150 Olson Memorial Hwy, Suite 400, Golden Valley, MN 55422) on the Third Thursday of each month at 6pm.


Tomorrow night (Thursday, 2/21/08) is the next XNA Twin Cities User Group meeting and I will be giving a presentation on the MinMax algorithm in Drop In. It should be pretty fun, there will be some pizza and swag (including some xbox games) and a few other speakers talking about some other interesting AI topics. If you’re in the area you should definitely stop in and learn about XNA!

Here is the main link

And be sure to RSVP so we can guage how many people will be there and get the appropriate amount of pizza.

Drop In


Last night I attended the monthly Twin Cities XNA User Group meeting. Instead of having a single presenter we have six members of the group stand up and talk about some projects they’ve been working on for 15 minutes or so. I have a feeling that everyone could have just gone on and on about what they were doing but, alas, there was no time.
I gave a presentation of the XNA game I have been working on called Drop In. Drop In is a pretty simple game with 3 screens. Also all of the artwork was created with Paint.NET and the music as created by Zach Adams along with some of the sound effects being created using a free tool called sfxr by DrPetter. So you can say that Drop In was created entirely with free tools!
Main Menu
Main Game
The source code is broken up into an engine and Drop In specific projects. Currently it will only run on a PC but with some minimal hacking you could probably get it to work with an Xbox. I think the main problem is loading up XML files for settings off of the disk which I’m not sure if it will work.
One of the most interesting parts of the game is the AI used for one player mode. I created a reusable MinMax evaluator in the game engine library. I looked at a great applet created by Yosen Lin at Berkley as a reference for improving my implementation of the MinMax algorithm with Alpha Beta Pruning. It actually seems to work pretty well too. There are some deficiencies with how I evaluate states I think and also there is a problem where the computer will evaluate all states and determine that every move it makes will result in a loss and therefore it ends up making an effectively random choice. It doesn’t account for human error and should still probably try to pick the “best” of the losing moves.
Anyway, I have posted the code in its full form so you can play Drop In and also as prebuilt binaries if you don’t care about the code. You’ll need the XNA runtime to play it or the XNA Game Studio 2.0 to build it. I have also posted just my game engine in case anyone else is interested in creating a 2D game or just taking a look at the MinMax algorithm I have created in C#.
Next Steps
Next month’s user group meeting might focus on AI if so then I can talk more about the MinMax algorithm I implemented for anyone interested. I might actually be looking to improve this AI a little by then too, I’m thinking of including some sort of mechanism for machine learning for example. I am also toying with some ideas for changing the goal of the game and adding in some features for complexity. For example perhaps the goal shouldn’t be to just get 5 in a row but instead to get as many in a row as you can when the board fills up. I’m also toying with ideas of special pucks that do more than just drop, such as pucks that push other pucks down and pucks that blow up and pucks that change the colors of other pucks. Etc.
I also want to make the AI evaluate the state continuously, not just on the computers turn and include the possibility of network play… which should be pretty easily actually since I have abstracted the players pretty well.
If anyone out there has any motivation to create a 3D Puck model for me I’d be pretty happy about that! I’m looking to take this game engine (and Drop In) to the next dimension and to do that I will need some good models.