Double multi is not really the case. People will just milk the double exp to the max and feel that they grinded enough for next few days so actually you would see less players on EU1 during next few days and even if you put 2 x multi for just like 2 hours, then it wouldn't really make any difference for most of the players as it's 2 short period for most to be noticed and I don't think it would make server more populated.
Even if it brought more players for some time, they would probably play less later, after double exp is gone. Grinding is important for many players (that's why your idea was supposed to make more people play at the same time)
Instead of trying to gain players by giving them better grind ability, we should focus on making game more pleasant. For example lowered fog chance would be great not only for the melee fighters but also for ranged who bleed their eyes out while trying to see where their projectiles hit. I seriously have seen more fogs in this game than in whole my real life ...
If we really want the more multi thing, I suggest the multiplicator could be based on how many people are playing at the same time which means that if there was +90ppl on EU1 you would get x1,2 multi and the number going through 130 with x1,5 up to 160+ with x2.
The values that I've just mentioned were just quickly estimated and weren't thought thoroughly but basically an idea is to reward big amount of players with multi, not starting multi for players to come. Actually as amount of players on EU1 is on the crpg website, I strongly believe it wouldn't be hard to code it. To be honest this could also apply to other servers with big playercap.
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