>>713665938A college kid fucks around with science crap in the attic of his uncle's shop with his fat friend. They by complete accident invent a way to send text messages to past. Doing this fucks up things a la the Butterfly Effect. The main character possesses the unique ability of Steins;Reader that lets him notice the timeline shifts every time someone uses his time machine. He is even able to gauge how far away the world is from its original state.
Inventing the time machine attracts other similar age people to his private science club like bees to the honey. Not everyone is what they seem. Ultimately the MC is responsible for making the choice whether to divert the timeline or attempt to return to the original timeline.