Hours played: countless
My connection with Master of Orion is nearly as strong as it is with Civilization. I player Master of Orion (MoO later on) 1 as soon as it came out. I sank hours over hours into that game. Later I played MoO 2 alone and with friends, had great times even though in retrospect the galaxy was really small. The animated little dudes seemes very real for the the age and time of computers it was made. It was 1996 I mind you.
The leap from '93 to 96 was huge. The game looked and looks so much better.
Then there is the great devide between the people who liked MoO 3 and those who don't. I love Master of Orion 3 and I still like it even though it didn't age that well. But let me explain:
MoO3 has ground combat. It in fact has ground combat that can stretch over more than one game turn. You can decide if your people shall use biological, chemical or nuclear weapons. You can decide on tactics and so on. This is defining factor one.
Defining factor two is the fleet combat. You can't just build ships any more and send them of you have to plan scouts and warships and such into fleets and armadas. It makes it a lot harder but also more realistic.
And maybe the most important defining factor: Not all races could settle perfectly on the same planet type. The classification of planets is actually a grid and terraforming just managed to move the crosshair on said grid slightly.
And besides that? The buildings just were plain cooler.
Then around came Master of Orion (without a number) and I played that one as well. The review of it is further down as well as the playthrough. So let me just list what I like about it: The polish is great. I mean it looks cool and the voice acting is great.
Otherwise it's just Master of Orion 2 in shiny. So basically it's a big step backwards and not worth talking about.
Sadly my only playthrough of this is ages old and in german.