Hey guys,
we're a group of 8 that are about to begin a game project.
I'm looking for a freeware (or a cheap 1 time fee) production managing software/system which is web based that would suit our needs.
I've been looking at the different options at http://www.opensourcescrum.com/ and found some that seem relevant but not perfect, I was wondering if anyone here is experienced with those things and knows of a good suitable system.
I'm looking for a system that is able to redirect user specific tasks for each user, have it ordered by priority, have different status levels, be separated to different assets and able to handle uploaded pictures, replies and progress in general.
In other words, something that would be suitable for game design which includes graphical assets.

Any suggestion would be most appreciated,
thanks a lot !

I've used Jira (issue tracking system) with Grennhopper (Agile plugin for Jira) with good success in several small sized (4-12 person) teams. Its highly configurable, and if you host it yourself the license for both is $20 for 10 users or less, which is donated to charity. You can get a free 30 day hosted trial that takes about 2 minutes to get up and running (just make sure to get the Greenhopper trial as well, you enable it in the plugins area).

Its pretty complex and configurable, but you can make it as simple or in-depth as you want. I started out using just the very basic features and eventually learned how everything else works. It can do everything you listed: you can create your own priority levels, task types, "workflows" (which are status levels like open, in progress, and the connections between them) - and of course there are sensible defaults for these; you can attach files and make comments. There are great performance analysis tools as well.

Thanks guys ! Some of these seem very suitable, currently choosing between Jira and Redmine.
Thanks a lot !

Redmine

I've used DevTrack, JIRA and Hansoft. I like JIRA best overall.

They're all more-or-less usable, except:

DevTrack has horrible search functionality.

Hansoft's desktop client has stability issues.

I would've said Jira/Greenhopper, but for free, there's always Trello and its web based!
I found it lacking in the feature department, and some of the things you've listed it can't do.
If you do have a small team, Jira can be pretty comprehensive with smaller number of licenses, and its upside is you may opt out of their service which means you could get away with a valid/legal license for a one-time payment instead of an ongoing fee.

Hansoft works well too, but it won't allow you to couple your bug database into it efficiently (assuming you intend on using the same tool for both) and the custom workflow is more powerful but less adaptable once customized.