We came late to this show and finally finished the 3rd season. As 80's kids, it made us quite nostalgic. It is a period piece about some kids growing up in the early 80's in small town Indiana. They play D&D, go to the mall, and ride their bikes. Unfortunately the local government science lab opens up a gateway to an alternate dimension that contains monsters. The same lab also has developed children with telekinesis and telepathy. One escapes and the nerd quartet find her and help her. The brothers who made the show clearly love this time period and the films and TV shows that it created. (Reminds me a little of "Ready Player One".
Caveat: This show can be disturbing at times with children being taken, and monsters hunting humans, but I liked being scared.