Thank you for your considered review, and for playing.
The menu transition was a quick and dirty shader I had on hand, intended to prevent the player cheating "time".
My biggest challenge was in ensuring the spawns won't crash in their first 60s. This involves optimising a lot of forward simulation; most of the game-overs, in this version released, are slightly premature.
I am still learning which upgrades are worth it. You could take a screen shot before pausing... My apologies for that inconvenience.