Yeah, only about half of the franchise seems to be available. All of it used to be shown as reruns on broadcast TV but broadcast TV hasn’t shown them in two decades 🙁
What’s new is also highly self-referential: they make jokes about the cliches all the time. It also confirmed that Pup is canon and takes place in the mainline franchise and even brought Roadrunner and Coyote into the universe. By extension, Bugs Bunny now exists in the Scooby Doo universe as he filled in for Roadrunner once.
The Day After Tomorrow has similar absurdities. Granted, I haven’t seen it yet.
The Alpha Test had a good concept but the implementation wasn’t at all good. Can likely be skipped and why I don’t generally watch newer films. It didn’t have any campyness to make it enjoyable to me and the acting was terrible.