I'm one of those people who prefer to not have real world/non-Sims related things in-game. But with the different "versions" of Supernatural out there, I'm not sure what I'm getting ordering the game.

I know there is a peashooter for people who pre-ordered the game. I also know there's bonus Plants VS. Zombies decor items if you ordered the game through Origin. And then there is also registration rewards (a PvZ poster and shirt, I believe).

What I'm asking is, is the "limited edition" just the peashooter-packaged one? And does it work similarly to how Pets Limited Edition was, i.e., you redeem a code on The Sims 3 website that allows you to download those items, like game registration rewards?

I apparently bought the limited edition and got the code and redeemed it. I got the PvZ outfits and the pea shooter.

I can't speak for the Origin version, but all the "extras" in the Limited Edition have to be downloaded and installed into the game. If you don't want them, you don't have to have them.

As stated above, it works just like the Pets Limited Edition (redeem code in box). This is the same as for Showtime as well (the extra big venue, and the "special" DJ booth).