Lost to the 4x strength Unbidden.
I despise the early spawn chance mechanics. That means that if you get them early, you're short usually 30-40 years of prep time, and that makes fighting them an order of magnitude harder. If they instead show up at endgame + 50 years as normal, you stomp them. Not much in between. Oh and it also means you almost always get the Unbidden. On all crises mode, you get them first almost every time.
I was trying a xenophobic void dwellers no planet run, which means I was limited to my starting species only and habitats and ring worlds. I was expecting it to be hard and dialed the difficulty down from 5x-10x, but still got trashed because I couldn't get my net alloy production above 600 per month even by 2430. Each battleship lost took 3 months to replace, and I was losing 10-20 per engagement.
Each habitat can produce up to maybe 200 alloys per month if min-maxed, but by the end game you have so much trouble growing pops because of the stupid empire-wide pop growth slowdown mechanic that if you're short on alloys then it may take 20+ years to get a habitat actually producing anything meaningful. And you suffer on consumer goods production too, so you have to waste habitats on that. By the time I lost, I only had 11K research per month and about 560 net alloys per month. That was despite being given a ruined matter decompressor too, which saved me tens of thousands of alloys to get to that point...
Ugh. Guess I'll wait for the next patch and try again with a different build.
Stellaris.