*spoilers* Why wouldn't Alex...
...be interested in finding out about the foursome when he got back? He knew they would enter the game in the future, and it didn't seem to be that big of a town. Seems like it would be pretty easy to locate people by the name of Spencer, Fridge, Bethany, and Martha at some point in the 20-some years. Especially Bethany.
Just seems to me he would be curious about them. I know I would.
Also, it makes sense that the game ended up in the school's junk room, since there was no reason to tie it to Alex's disappearance. But once Alex came back, it seems that the history of the game would've changed, since he knew how dangerous it was. I doubt that it would have ended up in the junk room in that altered timeline.
And one more thing: What was Alex's wife doing in the original timeline? She was probably married (to someone else) with a couple of kids. So now those humans have been erased from existence.