From 100 to 30 reputation due to a bad week...

[Cile]

Bandido you can lose in 3 plays very quickly, but I think in order to raise your karma you would need to be playing with a friend who is helping you.

Turing Machine you can lose immediately on your first turn by making a wild guess, but it would be impolite to do so with Randos

[nik592]

I mean, maybe I'm just being overly simple, but just play the games you like to play in non-Arena mode? Short ones if that's what you enjoy, but either way, actually play the game. I personally would find it annoying playing with anyone who seems to be trying to lose as fast as possible (and would likely red thumb them, not that that will affect karma, but if you annoy enough people, that could also be a problem).

[Jellby]

What's the fastest game one can finish?

Last time I tried, solo games (non-friendly) also raised your karma. Some solo games you can finish (usually losing) very fast, and maybe even concede.

[DoctorFianchetto]

I don't know that it's the fastest, but Yahtzee (in its many variants) can probably be done in under 10 minutes per game.

Yahtzee is pretty quick.

I personally play Captain Flip for karma boosting - which I play anyway, far too much. Most games last under 5 minutes. Seven Wonders Architects is also a quick 'un.

To clarify, I didn't mean finishing as quickly as possible by throwing the game early, rather playing a complete game.

[Weirdsewing]

Sushi go is a quick game.

[Hagardunor]

There are even faster (and non-premium) games you can play and finish.

What's the fastest game one can finish?

Domino is also one good option

[Jellby]

I can now confirm that just conceding a (non-friendly) solo game works.