I just reached the max designed level and I have some comments.
Tainted trixter is correct that there could be more stuff between space and the end, it is basically empty.
Also, wood is better than gunpowder, leave that stuff alone.
The stone transport capabilities of your elephant are the only real bottleneck that is left. I recommend adding some kinda crane thing on the side of the building, like a butchery with rails in the roof to slide large quantities of rock to the cutter.
Golden bricks are almost always worth it, when you consider how much of your building is going to be already built. At some point, you can reliably build back to where you were every reset within minutes. That is with or without the science boost to just have completel levels.
In space, I recommend additional stone-harvesting from asteroids. That is, not stone being put on the quarry pile, but a platform in space to resume the stone making cycle there, with the ground stone being used to dig deeper instead.
An addition to resets could be a transcension-like mechanic allowing for world-transitioning portals to be built in geostationary orbit. There, exotic new ressources could be used to continue building values.
Overall not even close to as fun as the cogwheel games, but it could get there with some more depth.