So... sometime ago a thread crossed my screen with someone wanting to work on Game Design, and one of you guys challenged him with a few design problems. I could not post at the time (I usually play in dev-forgotten EUW server, didn't have forum permissions here) and I can't find the thread now. Here is my approach to solve one of those problems:
How to encourage players to stay in the game instead of going afk
Reward them for consecutive played games without going afk. If you play let's say 50 consecutive games without going afk you are rewarded with a ward skin. A different ward skin is unlocked at higher numbers of consecutive played games, let's say at 100 and 250 games.
You are allowed to disconnect from a started game and don't come back once or twice every 24 hours with a small penalty towards your next goal (the next 10 games will not count towards getting your next ward skin). This allows for the normal service and personal problems that arise from time to time without hitting too harshly.
Maybe maximum of twice per day but restricted times in a week, you will not want to punish on second disconnect because people would stop playing after the random disconnect in fear of the next point, but you would want to restrict it weekly so people don't use that as a free leave game card.
So... I said punish and you won't want to punish people for going afk without being able to assess the reasons for doing so, sort of. If you fail to comply with the previous point and disconnect without coming back more times than allowed, you just lose one rank in your rewards ladder, losing access to one ward skin and having to play the necesary games without going afk to regain the skin ward again.
<>Custom games should not count towards this rewards.
<>It would be nice if you could activate your ward skins and view your progress on the profile section (a new tab) instead of using the shop, you want visibility on this.