Well formed Dude. I still say, you can win a game against the built in AI without any fleets (sadly). You need a few (2-3) ships for some reconquering: if the AI captures one of your planets, it will place some troops on it, then it leaves. You go back, bomb down the troops, and you regained the planet. That increases your reputation on the whole sector, and after a few reconquering, you have got a core sector! All core sectors can be taken this way. And if you have the these sectors, you won the game. The AI will have only a few planets in the outer rim. Some transports with saboteurs could easily overtake those systems. Fleets only making things faster and more interesting. Not really vital. Now, this wont work against a human opponent of course. And, I don't like to do that. It's more fun to build large fleets, and battle with them in space .. I just experienced this in my last few games. You can know, what the next step of the AI will be. Sadly..