Such nonsensical results. It really is a popularity contest.
At this point, I think it's clear that voting restrictions of some sort are necessary. My first thought: players can only vote in a category if they've got at least 5 hours of total gameplay distributed amongst at least 25% of the games in that category, with a minimum of 30 minutes of gameplay per game.
I literally only voted on one thing by accident because the button made it look like I was going to go to another page to choose my vote in that category. Turns out I was just voting for the game I was looking at immediately and irrevocably.