Great Game. No real complaints. (followed by several paragraphs of complaints)
Just have noticed a few things with spies. Spies in general are either too inexpensive at the beginning of the game or too expensive later in the end. The cost of a spy should be fixed. IE: 10000 bc generates a spy. Spy cost based on economy allows weak economies to still generate spys at the same rate as strong economies. As it stands now. As soon as my economy becomes stable (more coming in than going out) I max out my spy $. Generate all the cheap spies that I can to save for later when they become more expensive. As my economy progresses I reduce the spy $ until the other races start spying on me.
Also spies are actually being treated more as sabatours. As sabatours they are too cheap/cheesy. A group of sabatours can reduce a High - Population planet from 20,000+ to 6,000 on non capital worlds in one turn by disabling all extra food production. Without a declaring war I might add. I personally have "Killed" over 10000 people in one turn just by placing spies on two advanced farming tiles. As a before war strategy this may become too much of an advantage killing people both reduces economy and defense strength. Plus unless the targeted races has enough spies in wait to nullify all your spies you can remove your spies on the next turn after they have destroyed the population. Allowing you to reuse/abuse this tactic.
I have thought of several different ideas that could be used to attack this. Two simple and two more complex.
1. Leave it alone but teach the AI to take advantage of this too. It could make for an interesting end game watching populations go from large to small.
2. Make food tiles non-spyable like colony tiles. (Probably the easiest of solutions).
3. Make two classes of spies. Spies and sabatours. Spies "learn" about other races and protect from sabatours. Sabatours damage other races improvements and are 1 time use only. Make sabatour levels a research tech. Generic Sabatours 10 - 15 % damage. Advanced Sabatours 25 - 30% damage. Highly Trained Sabatours 40-60% damage. Suicide Bombers 70 - 90% damage. In each case the improvement may still be functional; however, it may require repair (it reenters the building que with a cost to fix). The cost of each tech and training would be scaled accordingly. I may take 5 turns to make a generic spy but 100 turns to make a Suicide Bomber. (or make spies upgradable like ships).
4. Make each spy a fixed cost but add some type of a cost per turn to the current spy system. IE. To put a spy on a Capital/Galactic Improvement costs (Large # of bc) per turn and disables the improvement bonus. To put a spy on a Research Improvement costs (Small # of Bc's) per turn does not disable the improvement but has a x% chance of stealing a tech(s), where x is increased the longer the spy is present on the improvement. To put a spy on non-research improvements costs (small # of bc) per turn and disables the improvement.
Also there is not a way to just snoop on your neighbor. I don't want to have to damage my neighbors' improvements just to find out what ships they are building or economic strength.
However do not take any of these ideas wrong. The current spy system is good but in need of some balancing. And as most people would find there are several ways to accomplish the same thing. These are just my ideas.
On other notes. No serious game play problems. I have encountered the buffer overflow on exit and the bug that reverses the screen. However, I did/have not exited the game for that bug. I Alt-Tab'd out and Back and the screen returned to normal. No CTD's.
Keep up the GREAT work.