--- maraxsis-classic_1.33.3/prototypes/technology/water-treatment.lua   2026-09-08 20:01:53.000000000 -0400
+++ maraxsis-classic_1.33.4/prototypes/technology/water-treatment.lua   2026-09-13 16:05:42.000000000 -0400
@@ -112,7 +112,7 @@
     categories = {"chemistry", "cryogenics"},
     main_product = "water",
 }}
-add_to_tech("maraxsis-water")
+add_to_tech(data.raw.recipe["ske_h2o"] and "ske_h2o" or "maraxsis-water")

Technically whose two recipes do the same thing, but for me kse_h2o requires Vesta (Secretas, Aquilo and a dozen other planets) while Maraxsis needed much less. I don't mind either recipe, but unlocking hydroplants in this case should also unlock ske_h2o.

I backported this change from modern Maraxsis, because it seemed to be something NotNotMelon intended to have as cross-compat and was recently fixed on their end, but I hadn't taken a closer look at the actual implementation, just enough to know that it didn't crash under any conditions.

Might have to change something about that, because yeah, Vesta is locked behind more planets compared to Maraxsis (though this should also be an issue for modern Maraxsis as well?)

After taking a closer look, I'm not sure this is an issue? Or at least, not a Maraxsis-Vesta compat issue.

Having both Classic and Vesta enabled, shows the ske_h2o recipe as being unlocked by the Hydro Plant tech, as well as Vesta's "Working with gases" tech, with default settings. I also tested with shared gases enabled, then separately with Complex Mode disabled, and there was a water recipe available on that tech either way.

So I'm not too sure what the issue is here. If you are only looking at the code; that add_to_tech function literally adds the recipe to the tech that is defined at the top of the file (in this case, the Hydro Plant tech)

Hmm... Well, the old recipe was locked and the new one didn't work. Reverting the fix and looking more carefully - it didn't work because gases inputs are flipped. At least the fix is trivial. Sorry for the noise.