The counter went up quickly during the last 30 seconds, which made me believe I was going to make it. If I only had 5 or 6 more seconds on the clock... multiplier was set on x15, but I created the 4th nexus too late into the game apparently. Grrr... =P
Lesson learned: more nexusses (nexi?), less upgrading on them!
@MrDayCee - yep. Upgrading them a few levels is fine, but a good rule of thumb is that if you have to terraform more than about 3-4 squares to get the next nexus upgrade, it will be easier and cheaper to just build a new one. A new level 1 gives you EXACTLY the same points as upgrading one a level, and is usually considerably easier to pull off.
The quantity of nexuses has been good advice, but it took someone pointing out the use of PAUSE for me to finally get this last quest. Why I didn't think of that myself, I don't know, but that made a huge difference. It was still kind of close but now I can focus on other quests.
Just discovered a bug in this old game. On level 4, I originally only got 1 star, so I redid it and managed to get 2 stars. Finally, I managed to get 3 stars, but it won't show that I got 3 on the level select screen. It's stuck at 2 stars. I tried again, and again got the 3 stars, and it still doesn't show it.
Just an update after the bug I mentioned in the above post. I just decided to come back and continue my game, and now it shows the 3 stars for level 4. So if anyone else comes across this bug, just refresh the page and it should appear.