Well to get 20 upvotes in only a few hours is "hotter" than 100 upvotes over an entire year, don't you think? And indeed mixed channels can play a role, as when channels are mixed I could see some memes getting higher ranked because that channel was less often visited in general. I wonder if the poster's rank also plays a role or not. Let's say I work as a moderator for Game Jolt and I often get this question about the games posted there as well, but you already guessed it, I'm not allowed to reveal about the formulas there, but I can't rule out some secrets things play a role here as well.