The file roughly doubled in size from 1.5 (6,890 → 12,570 lines; ~130 new functions added, only 4 old ones removed). it's a near-rewrite of the procedural universe + save systems, plus several new UI features.
I think i will move on to new projects soon and just come back to bugfix this every once in a while at this point.
New player-facing features
Tutorial: Walks you through exiting Earth's SOI by building a basic rocket, pressing launch, and waiting. A 3 year old could do it. Super easy.
Save system overhaul: I redid the whole saving thing. Theres now 3 save options on the menu, savestate cheat, and autosave in the Build menu. It exports save data like any other game. If you can decode it you earn the right to edit it.
Build tools: Symmetry toggle. Places on the opposite side. Drag toggle. Places when you hold click. Autosave. Auto saves your build every 5 seconds.
Rarity/discovery system: procedurally generated star systems now have rarity tiers (common/rare/epic/legendary). Each one has it's own special track - go explore. You'll get notified if you generate a real rare system like Epic or Legendary up top. And there will be an arrow pointing to it. Epic and legendary systems have crazy features. Watch out.
Navigation aids: Rewrote the whole nav beacon code. It should not miss anymore and shouldn't lag anymore. Even for really far away objects. Really far away.
Proc Spawn: It's a new thing. If you zoom out to galactic levels, you'll get a galactic star spawner. You can spawn thousands of seeds a second, as much as your PC can handle. Try to render all 1 million. I optimized it for ages. I could NOT for the life of me ever get optimization good enough to run it on my PC, atleast.
Under-the-hood engine changes
Orbital mechanics rewrite: Everythings gone and replaced lol. Works better now. Makes alot of sense and stuff.
Warp speed restrictions: Logic computes max warp speed instead of hardcoded bounds so you aren't stuck in a SOI with a tiny timewarp maximum.
Procedural universe generation - We had this in basic in 1.5 but it was garbage. The whole thing is mega optimized by hundreds of times now and basically doesn't even resemble the original.
Rendering performance/LOD system: Draws far away stars with a level of detail less the more zoomed out you are. That's the way you get 60fps with 5k stars loaded.
Minor
Menu redone with all of those new things listed. Yay.
Version string was updated to R1.6.0. Obviously.
Full Changelog: R1.6.-1...R1.6.0