Yeah, it's surely a bug with Smart Investment. Some upgrades may make production 0, but not this one. I'll look into that.
The last 5 upgrades are currently placeholders, as you surely noticed. I plan to make it possible to reach EH 7D with them(within this universe timeline) and make it the end of the game. Currently the endgame is not finished at all, so I totally agree it's not engaging as it is now :)
Would you like to see some other essentially new feature by within the last 5 upgrades, like a new hypercube? Or would good upgrade-driven progress make it good enough?
