I dug up my old account from when I was a kid, just to congratulate you on this game. It's definitely the most well-executed browser game I've played. I have a few criticisms which I hope can help you improve it more. To be honest, I nearly stopped playing at the beginning - I'm glad I stuck with it, but yeah...
So firstly, it can be difficult to see where you have put electric cables and water pipes! I beat the game, but a lot of times I spent ages trying to work out why a building didn't have power or water, then eventually figured out the line was missing a square. My eyesight isn't that bad! This should be clearer.
By the same token, if the 'free power' and 'free water' showed how much was actually free, instead of the total being produced, it'd be easier to manage those aspects.
Also, as I really enjoy the sandboxesque play-style, while the missions (esp timed ones) are challenging, I would like to be able to play freely without being constrained. It would be really awesome to increase the scale, and watch hundreds of my little mars dudes doing their thing. I felt like I was just getting happy with my colony by the end of each mission. Good to have structure though.
But really I hope you develop this further, as it's the most I've enjoyed any game in recent times! I'm sad it's over!