In one of the mailboxes of the houses, you can find a package. On the plaque are some strange symbols which as of now are not decipherable and may never be. It is unknown what it is hinting towards at this time if at anything. On the far side of the pond out of bounds is what looks to be a satellite with a golden plaque of some sort on it. In the full game, if you go near the church out of bounds in the game you can find a gravestone with a silhouette of the Neighbor's wife on it. Out of bounds in Alpha 1, there is a second version of the Neighbor's house which is used for the intro cutscene. Out of bounds in Pre-Alpha, you can find a burning house on top of a hill. This can be found in BP_Sosed (the neighbor). When you open the cue, it shows audio files of extremely vulgar language. In the mod kit, you can find a part where it says Swear Sound.
