What is an Overlord?

Try this site.

http://webpages.charter.net/trevorpowdrell/

The ships are listed in the "military projects" heading.

As for how far you get up the tech tree, that depends on your play style, map settings, AI difficulty, luck, etc. I play a diplomatic, builder-style game and my games often go past Avatar Technology. You can win on the small maps without ever even getting Battleships though.

Thanks for the link, very helpful. Next question: Has anyone managed to research excalibur tech and build some of those bad boys? If so, how do you prolong the game enough to get that far up the tech tree? Huge universe? Harder difficulty?

Simple -- huge map, low difficulty (e.g. set everybody on normal), refrain from significant offensives (military or cultural). Don't ally with everybody else, either. The risks would be that the AIs surrender to you too early or get dwarfed by your culture, so just avoid clobbering them as much as you can.

You can find all the ship stats in your Data directory, in the .ship files. They're pretty readable.

It's been researched before - it's quite close to the Final Frontier technology required to win the game. However, it's not likely to be researched as most players would shoot towards Final Froniter instead (unless it's either disabled or for some other reason.)

The buildtime for Excaliburs is quite high - around 3000 production units. Although they are expensive to build, it's possible to build them on a planet that has all production enhancement upgrades, wonders and capitals.

Personally, I just ignore Excaliburs. By the time I can research them, I could just aim for Final Frontier instead.

On higher difficulty, the AI handles its economy better (or gets outright bonuses at the highest two levels) so it researches faster. Larger maps longer-lasting games since there's more galaxy to conquer.

I've never had a game where I *needed* Excaliburs, though I've had a couple where I built them just for fun.

My second-to-last game I needed Excaliburs. The Drengin had about 55% of the galaxy, I had 45%, and they started their Overlord fleet towards my stars. Two Excaliburs still gave me an official military rating below the Overlord fleet, but an Overlord is really no match for an Excalibur.

(Particularly when I destroyed all the Drengin starbases sitting on military resources on the first turn of the war)

There was a problem with statistics not refreshing until a turn or two. ie. If you destroy military SBs, the AI would still have those bonuses for another 2 turns. Wonder if it has been dealt with.