Although Master of Orion: The Boardgame proved a crushing disappointment for me, it is a game that could potentially lend itself to solo play. There was a discussion about this on BoardGameGeek’s MOO page some time ago, in a forum entitled “Anyone working on a solo variant?”, and as an alternative to just playing the game to see how many VPs you can get, Ian Toltz put forward a suggestion to help simulate the potential fleet strengths of your AI opponents. I’ve expanded on this a little here:
(1). Before you start, you’ll need to remove the following 16 cards from the Structure Deck (all of which target your opponents):
Red Structures: Battleship, Death Spores, Orbital Batteries, Titan, and Troop Transport (10 cards in total)
Black Structures: Destroyer, Espionage Training Facility, and Spy Center (6 cards in total)
Then, if you wish to make it slightly more difficult, randomly remove up to 16 more cards from the Structure Deck (I’d suggest removing just 6 more the first time you try this variant) before you begin.
(2). Roll 3d10 in Rounds 1-3 to simulate AI opponent Fleet Strengths for that round.
(3). For each Fleet score that is higher than yours, they will all attack you at the start of the Action phase — if your Fleet strength is higher than theirs, you can attack as per normal rules during the Action phase if and when you wish.
(4). For Rounds 4-6, roll 4d10 and add +1 to each roll and follow (3) again.
(5). For Rounds 7-8 roll 5d10 and add +2 to the highest two values and follow (3) again.
You’ll need to decide on your own sliding scale as to what constitutes a good target score, but I’d say 30-40 is a worthwhile starting point, but this is wide open until you’ve got a few games under your belt.
I’ve also done a one-page reference sheet (not for this solo suggestion btw) if anyone thinks it’ll help during a game (downloadable under Files in BGG entry: Master of Orion).
Hope that helps!