Here's my detailed bug/feature list:
Enemy Anomaly ships should not be called "USS Corvette Fortune". They should be called "Drengin Corvette Fortune", or the AI should rename to conceal that this was an anomaly ship.
Minor races should not be allowed to destabilize a major race, because a major race is not allowed to destabize a minor.
If your trading partner gets culturally assimilated, you get to keep your trade routes, but some of the other information can get corrupted. In one game, my trading partner was the Alexians who were culturally assimilated by the Drengin. I got to keep my trade routes, but the income went to zero. I had to break and re-establish the route. The planet that converted was the Alexians' only planet.
On trade routes, the "year established" says N/A. The documentation says that older trade routes are more valuable, but it isn't clear there's an in-game benefit. Does the trade route get a bonus for the number of circuits the mini-freighter completes? It would be nice to see a detailed breakdown of how trade route income is calculated.
There is a design bug with trade starbases. The mini-freighter moves like an ordinary ship. However, the trade screen indicates that the mini-freighter path is a straight line. So, the player can be misled into placing trade starbases in a place where there is no benefit. Further, optimal use of trade starbases means that you have to stack your trade routes between the same pair of planets, and choose a horizontal or vertical line. It seems wrong that you have to choose horizontal or vertical trade routes to maximize trade starbase income.
When choosing "random" AI alignment, the alignment should be concealed at the game setup screen. Further, the in-game messages should conceal alignment until you reach a certain level of trade or espionage. For example, evil races could pretend to be good.
How about making the tech costs randomized? For example, "Diplomacy" normally costs 120. Instead, the range for diplomacy could be 100-500. This way "rush to Diplomacy" has the potential to backfire. The tech costs could be randomized per-game, or even per-race. Perhaps some techs should be randomly added or removed each game? I'm thinking that maybe 10% of the time there should be a great defensive ship available early. Maybe an extra terraforming tech should be available in mid-game sometimes. This would increase replayability, and prevent players from always following the same tech path.
When the AI destroys a resource starbase, it should have constructors prepared to claim the resource immediately. It's too easy to steal resources from the AI during a war.
At a high enough level of espionage, the player should be informed of all AI trades.
The AI should propose trades that are more complicated than single tech-for-tech.
There should be a button on the trade screen that automatically balances out a proposed trade with the correct number of BC. The same effect can already be achieved with the sliders, but it's a bit tedious.
At a high enough level of espionage, the player should get to know United Planet resolutions in advance. The human player should get a chance to trade influence before the UP session.
At the start of the game, it is possible for not all races to be at the first UP session, because the human player has not yet contacted them. Any major race that any UP member has contacted should be invited to the first UP session, even if the human player has not contacted that race.
Because of the tax income cap of 4xPQ, there are situations where an economic resource provides no benefit. Getting an economic resource or the galactic stock exchange should raise the taxes cap by 1xPQ each (not sure what amount is correct). Some social projects and racial abilites should also increase the taxes cap.
In general, production capacity tends to increase a lot faster than income. Production is capped at 10xPQ and taxes are capped at 4xPQ. Many new players find it confusing that they can't fund at 100% for the entire game. A player who manages their economy well should be able to fund at 100% for the entire game.
Remove the hard limit of 10 trade routes; adjust it based on map size. Taking the +trade route racial ability should allow the player to go over the limit.
There should be a "trade good and wonder" summary screen, so you know who has what.
There should be a "tech summary screen". When trading, I like to know (a) What techs I hold exclusively (b) What techs I hold, but are also held by another AI. This helps me decide what to trade. The information is already available from the diplomacy trade screen; I'd just like to see it summarized in one place.
There needs to be a resource summary screen. I always keep track of where the resources are in a notepad file.
There needs to be a "find system" feature. There should be a "find uncolonized planet" feature.
There should be a lease summary screen, and a tribute summary screen. I'm not sure if the Mitrosoft leases expire properly. On one tiny/rare tech win, I was sure I had played enough turns for my mitrosoft leases to expire (40 years), but they didn't.
Since fleets get a bonus on defense, the amount of the bonus should be displayed onscreen somewhere.
At the start of each turn, I should not be required to cycle though every planet that just completed a ship. There should be an option to eliminate the military-completion popup just like there is for social projects.
On the research screen, it should indicate the % completed, just like you get for military and social projects. When trading, I want to be able to avoid trading for a tech I've 75% researched, but I may trade for a tech that I've 25% researched.
When the AI proposes a trade, I should be allowed to check other screens before deciding whether or not to accept the trade.
There should be a warning given if the player's approval rating drops below 50%. The same information is already available, but it requires checking the economics screen every turn.
In one game, the race icon for the I-League did not load, and the diplomacy screen said "String not found". Their planets were displayed as a blank star.
Once a planet gets a skull-and-crossbones icon, if you later become the dominant culture in that sector, the skull-and-crossbones should go away.