Board Game Arena

I just played a game and won. Gained 13 points but the other player lost 26. I have seen this type of scroing before.

Some players gain 50+ ELO points in one game, how?

Any idea why this happens?

In your early games the ELO you gain or lose is doubled to let a player align with their actual skill level fairly quickly - thus your opponent losing 26 to your gain of 13. After a certain number of games it switches to a more normal rate.