[2023] Multi-player Horde night madness?

Party gamestage multiplies a little oddly, +1 player is actually the biggest leap in difficulty, and it trails off after that.

They get sorted from highest to lowest, then multiplied by the starting weight with the weight being modified down with each additional player.

Here's the blurb from the gamestages xml:

Originally posted by Gamestages.xml: This is how the game stage (GS) of a PARTY is calculated:

The GS of all players in the party are calculated.
The players are sorted by GS.
The highest GS number is multiplied by "startingWeight".
This then loops down the list and "startingWeight" is multiplied by "diminishingReturns" every time.
The final result is then converted to an INT that rounds down.

Example:
Players with GS 204, 30, 60, 91, 5, 1, 2, 80
startingWeight= 1, diminishingReturns=0.5 (defined in this xml file below)

So we get
204 * 1.0000000 = 204
91 * 0.5000000 = 45.5
80 * 0.2500000 = 20
60 * 0.1250000 = 7.5
30 * 0.0625000 = 1.875
5 * 0.0312500 = 0.15625
2 * 0.0156250 = 0.03125
1 * 0.0078125 = 0.0078125

...for a total of 279.0703125 which is then rounded down to a GS of 279

So you and your friend had the same gamestage, So it's your gamestage plus half of his, which puts you quite a lot higher as a party than when you're seperate. Couplet hat with the blood moon count being per player as Jost said and, yes, what you experienced is pretty normal.

It can be overwhelming for sure- But it can be contended with now that you know about it by enhancing your fortifications to compensate. Or build two seperate bases. You'll want them to be more than 100~ blocks apart, Or you'll be considered in the same area.

For what it's worth, you could have one base you both live in, and then two horde night arenas seperate from the base that you two go to to split up the difficulty, would let you get the best of both worlds.