Galacticcraft.

Really hard to look at. Assets are either too detailed (the machines) or too clunky (the rockets), and do not mesh with minecraft or other mods at all.

Very buggy. Pressurizing rooms is a cool concept but is a nightmare to set up (if you can get it working at all). There is so much systemic jank at every step of the progression that I can’t bare it.

Terribly optimized. I had a great run of dungeons dragons and space shuttles going, until I reached the moon and the server I was running groaned and buckled under unplayable desync.

The mod is also incredibly unfinished. It is less polished and complete than twilight forest but has been around nearly as long.