I had a plan in my mind to create Firefox Extensions using few games i had developed during(and after) my college days. Most of them were developed in Flash, so porting them as Firefox extensions aren't a tough task.
The addon is present here.
What is Knights?
Knights is a simple game in which you move the lone Knight in a chess board(in usual 'L' positions) and try to cover most squares. You cannot undo any move. The high-score is stored so that you can try beat yourself.
Is this a new game?
No. Few years back, one of my friends had installed a similar game in his system and it was quite interesting. At that time, i was actually exploring Flash. So i thought why not try to develop this in Flash and finally succeeded developing it after quite a bit of struggle.
I originally had developed this game more than 5 years back. It had too many frames(screens). I had to fine tune few things to make it look good as an extension. I used the same XUL(most of it) that i used in my previous addon and changed few colors to suit the flash content.
Like my previous addons, this one is also under experimental addons. You will need an account to install your copy. Install the addon from here.
After installation(and browser restart), a small Knight symbol will be added in the status bar. Clicking on it will open the Chessboard for you to play on.
Please report any broken feature, bugs and feature requests here.