Well I have enjoyed playing Moo, seeing as I have only recently discovered what a great little gem this game is.
Ironicly, even after all these years, I end up spending most of my time playing a game that has inferior, sound, graphics and controls to most modern games, but is just overall a lot more fun.
I haven't played all that long, so I still have a lot to learn.
My favourite species has to be the Darloks. Being bad is so good. Is there anything better than letting all the other races do the hard work and spending while you just build up missile bases and then steal all their technologies?

One problem of course with the Darloks is, when you make an alliance, some other race frames you and of course being a Darlok means the automatically think it's you, even when it wasn't.
Second favourite species is the Psilons - all the fast technology researching gives you a great lead.
I still have a few races to play with, but some do not suit my style of play.
My general strategy at the start of the game and this goes for almost every race, is to research propulsion technologies until I get ion drives and then to colonize every half-decent planet around me that I can. Any trashy planets with 20 max population or low minerals and such I leave alone. I usually end up with around 5 or 6 planets and by then the computer opponents are already venturing near me. After that I focus on building up missile bases to prevent any attacks on my planets (around 50 or so for each planet) This strategy seems to work well for Darloks (who can then steal other technologies) or Psiolons (who are the fastest researchers). I then end up having a technology lead and I go about inciting revolt on planets and then taking over those planets.
Of course things don't always go to plan and in particular with playing the darloks, I tend to get ganged upon.
I can't remember which ships I built, I am still trying to figure out what the different weapons and such do and which are useful or not, but I managed to build really fast large ships and I had weapons that half shields ability or something like that anyway, and I managed with a group of about 70 about of these to kill the Ship that guards Orion in 1 or 2 hits - Is that a bug perhaps, usually I find killing that ship a problem?
The person who posted about alliances is right. Whenever I make an alliance I get dragged into wars and what's up with opponents not wanting to sign non-aggression pacts and then afterwards begging for peace after you leave them with only one planet even though you asked them 5 times to sign a non-aggression pact.
No one seems to want peace.