Board Game Arena

That could maybe apply to betas especially, cause they are prone to those bugs.

Yet another option could be at set-up time: no abandoning possible. You either finish the game whatever the outcome or you quit with a penalty, with players knowing what to expect beforehand. These tables could award an extra elo in case of victory to encourage playing in this fashion.

FWIW, I like this option more than all the others discussed above combined... but we almost already have that, right? It is called Training Mode.

Training Mode:
* you can win, you can lose
* you can quit if you want, you can collectively abandon the game
* no Elo is won or lost in any case

Playing mode:
* Elo is won on victory and lost on defeat
* you can quit, but then you lose Elo as if defeated
* cooperative games abandoned collectively also count as a defeat and players lose Elo according to the last position in the game

The only new part is the latter. It removes the incentive to ultra-competitive players to try to convince others to abandon the game plus it adds an incentive to end the game in as good a position as possible, even if it cannot be perfect.

I like this option the most because it seems waaay simpler to implement than the others (I might be wrong), which means it has a smidgen of a chance of actually happening.