Not bad, but it's pretty buggy right now, and the only reason I can run it well is because I personally have a beefy PC.
Also, despite the name there doesn't really seem to be much "Growing" going on in the game. Only in the giantess sim mode, which... Is just one size change, which feels pretty tame for a giantess fetish game. I'd expect there to be more of that but, no that's pretty much it, just one alternate size and reverting back to normal.
The current free version, 0.9.2, seems extremely broken in many aspects. Only a few basic modes work, while most optional modes and features including the nightmare challenge level just doesn't really work. Whether it's because of broken AI or the map despawning pieces of itself after a few minutes (causing the giantess to fall through it which is what I assume causes the auto-loss in many stages with many settings after just a few minutes no matter what).
Also leveling up from collecting orbs seems to do absolutely nothing, which seems weird. Why is it there, then?
I hope we get to see a mode for each girl where they progressively grow over time, making it harder if you take too long as they can move across the map faster the bigger they get. You could reuse the GTS simulator mode's growth animations for that I'd imagine.
That aside, I don't want to be rude, but judging by the 1.0 sneak peek posts, it looks like the developer feels the game is pretty much finished and it won't really change that much going forward. out of the 10 supposedly "major" upcoming features mentioned, a good chunk seems really... not major at all, to be frank. Bit of a shame, but... oh well.
I hope 1.0 will be far from the end, because there's potential here for an exceptional game about this fetish... but it still feels like it needs a lot of time to cook to me. From bugfixes, optimization, to just aspects of the game that feel incomplete (levels doing nothing, lack of growth, etc.), as someone who discovered this game recently this really doesn't feel like it's close to a 1.0, with all due respect.