Hmm - which means the OP still has a potential problem there… 
Even unranked … we won’t find it OK to have “escaping” happening - unless arranged beforehand that its OK with the other player.
It’s a tough one to have a “no special considerations” answer for.
I think the OP’s suggestion of a group where the people agree this is OK is a fine way to go, actually: if they agree to play unranked games, and agree that they don’t mind if the game stops unexpectedly, then …happy days.
I believe there should be no problems with resigning a game that is unranked in the middle of the game, though.
Agreed. It might be seen as a bit rude, but I think it should be allowed. I’ve even heard people suggest that when playing unranked teaching games against weaker players, it’s a good habit to get comfortable resigning if you want to end the game and go to review, rather than asking the learner to, which makes sense to me
(bolding mine)
I think the OP may have meant resigning the game, rather than leaving it, but I’m not sure – in some languages like French and Spanish, the word used for resignation/to resign the game, is “abandonner”, “abandonar” etc.
It’s a common phrase transposing to use “abandon” in English to mean that, and OGS has the button to resign in accord with that, and that was how I interpreted their message.
Edit : Also as often is the case with autoimmune conditions affecting the nervous system, is it perhaps due to exhaustion/fatigue which comes on, or not being able to continue due to the strain of playing/reading/decisionmaking and that on the nervous system, that the games might be cut short (say in 50 moves) ?
I’ve played with some players who either often misjudge and resign games they are winning (e.g. after dying a big group but being still 20-30+ points ahead) or sometimes have to leave for unexpected reasons (so resign their live game) – in general, is that considered acceptable ?
“Often” is an important word here.
I personally have resigned games only to discover I was winning 
However, if I were reported for sandbagging in that case, I would not be offended, I would simply be able to confidently explain why I thought I had lost, and the moderator would be happy with that.
They would say to me “OK, I get it, please take care not to let this happen often. Maybe you need to back yourself better, and play a bit further before resigning”.
And they would be right 
To add to Eugene’s response, it should be understood that the large majority of rank-manipulating sandbaggers throw the game near the end of the game, very often when the game is over and ready for scoring. I strongly suspect that the reason for this is that they like to get the satisfaction of demonstrating a huge win before they resign or time out. This circumstance is, of course, easy to distinguish from a player with a large advantage resigning in mid-game.
There is also a difference between resigning 5 points ahead and resigning 80 points ahead, especially for kyu players
I’m also playing “for other reasons”,
but, I think playing like a sandbagger is not respectful of other players.
You can play honnestly and still play for fun or other.
And, your message suggest that your ask to be allowed to play like a sandbagger 
Strange.
I should block you if you do that.
When I resign when ahead, it’s usually after losing a big group and overreacting to that
It’s because it’s smelling coal in my kitchen
I said, I tried your solution before and got banned. If your solution can still get banned, that is not a solution. Your logic is still circular.
I’m confused. Eugene’s solution is:
Is that what you have done, and did you get banned because of that?
If yes to both, then message Eugene with what that account name was.
(Unless there’s some restriction from your current account being new, you can message Eugene
by clicking on Eugene’s username and then clicking the blue Message button in what pops up.)
You did not try it. You said yourself that you were still playing ranked, so chances are you got banned for that.
I got banned before when my ranked-to-unranked games ratio was like 6:1. I would play a rank game once or twice a week while playing 5 to 7 unranking a week.
Also, please work on your attitude here. You’re being needlessly agressive.
Perhaps you missed where I suggested that perhaps this was a misunderstanding at that time.
It seems you are not now clear what the rules are, so perhaps you also were not clear then.
Or it may have been a moderator mistake back then - goodness knows anyone can make a mistake.
The correct way to deal with this is to respond to my offer, here in PM, to talk about it 1-1 to discuss your particular situation and history.
(Chat on the main site is not ideal, that little window is bad for a proper discussion).
This discussion appears to have become circular and can be continued in PM between the original poster and the mod team.