Well perhaps the 1 year 94K tech win in a small galaxy is just this side of believable.
Well I hope those scores in a small galaxy are believable...

And what other component could he have increased by 4000%? Population? Hardly, even a 40 fold increase in pop is totally ridiculus but I'm also under the impression that your pop score is based on a logarithm of your pop and so a 40 fold pop increase wouldn't even do it.
If it were me, this is how I'd attack it. If playing a very short game population is where I see all the score difference between tiny, small and medium.
If you could hex edit to get farm space for 30 trillion people... the game kills them very slowly. It would take a couple of years for them to fall to normal levels. During the whole time you could tax them as well.... and if you gave yourself "perfect worlds" you would have no problems.
For instance... if you could give your worlds PQ40ish... you only need 20 spaces of VR cneters, or 10 spaces with VR centers and morale improvement tiles to hit the "magic point" where all population increases were covered because the morale forumla zeros out the negatives. Make the rest of the tiles +300% farm tiles...
I still don't know if there would then be a way to set all planets to max pop... but in theory once you hit the magic morale point on any planet the skys the limit as far as population/tax goes. If you had 30 trillion people in the first year taxed at 79%... what would your score be? Econ and pop alone.
It depends on what he has figured out that he can edit that they aren't running any check on. I can't believe they aren't doing a checksum on the score... which makes me think he might just be being clever in game. You could never get a score that high through production or research... and I doubt hes using starbases spam either. Assuming there is a solution which isn't direct score editing (why not end a score in a 7 or something to prove you cracked that to the developers... hackers like infamy) the best way to do it I think is editing population and being able to tax them hard early.
The reason I'm suspicious of a straight score edit is looking at those last 4 games. You get many less points for a tech win... I suppose he tried that first with whatever he is changing, and was impressed with the score. His next game wasn't getting greedy (the theory if he just edited score)... no, he tried his same cheat, but this time at suicidal instead of beginner and a mil victory instead of a tech victory.
The result of 2 mil probably blew him away!
The next two games with 300K+ plus scores are in quick succession... he's feeling out the ranges he can get with his cheat and trying different play styles. It looks to me like someone testing an ingame cheat, not like someone directly editing the number.
I come to this partly because I have run my own game company, and I use to have to deal with people trying to crack a high score system. Typically you could see the hacker feeling around, trying to find the max he could set something to show you how clever he was that he hacked something. Because after the 2 mil game the scores drop, I think he's testing an in-game cheat... not sending the devs a message.
IF its a military cheat somehow (adding starbases from turn 1 somehow?) I notice he goes very good every time, which gives a % increase to defense and HP. As both HP and def go into mil score.... that is the only thing to me that suggests it could be military and not pop.
Its a cheat of somekind, and I believe he's just bounds testing what he can do with it. Perhaps he's altering the score directly, but the pattern of the games suggests something else to me.
~ Wyndstar
P.S. you know, I should really switch to the diplomats. I talk to more of you guys on a regular basis and my empire has been dead for a while....