Every time a user loads a simulation, it adds one to the votes. Each user can load a simulation as many times as they like (The reload button does not count as a vote) This would mean that only the saves which get a lot of views will be high in the voting ranks.
The simulations at the top though will be getting hundereds of views though, so it kinda cancels it out. But yeah, perhaps a time restriction would further benefit the system.
@plypencil -1 There isn't really a voting problem. If I don't like the save, What do I do? There won't ever be vote downs. Voting Down is a sign of improvement.