Experimenting with editors for some years now. (mostly building maps for multiplayer). Well to be honest my first editor was "sim city" (I know its a game).
Advancing I released a campaign and multiplayer levels for "sudden strike RW" (I'm afraid these resources are lost). Next map I released was for warcraft 3 (if you are interested I'll look it up and upload it here).
Finally I created my first mod, simply because I made multiplayer-maps for BK2 and found out that the reinforcements are controlled by the game. So I started my first mod.