They should have a surprise monster in the core. When you make it into the core, the core starts shaking and breaks out 2 bosses. After you defeat the bosses you investigate what's inside the core. It turns out to be a portal, and when you enter it, you are stranded on a tropical island. Fortunately theres a haven nearby, and you just figured out theres an another arcade! The arcade includes new monster types: Water, wind, light, plant, bugs, and at the very bottom is another core, which is very different because it is much bigger and no monsters inside. After discovering a second core, a whole army of spiral knights attempt to fuel the crashed ship with the core but it creates bigger problems. The ship is destroyed and now they can't get out, but suddenly gremlins appear and start attacking you and the group. Which of course makes it an another battle. After defeating the gremlins, you find out that they got here by a working ship! So you and all the spiral knights board on it and blast off and escape the planets you crashed on at the very beginning! During the trip of the second arcade, there are 3 bosses that awaits you: A mighty hydra that is the water monster type, a queen killer bee which is a bug monster type, and a gigantic light orb that blasts in every direction!
Thats my idea of what happens in the core!
When you said Gigantic Light Orb, I gave up.
But I do admit you're onto something: A constantly expanding game. Like how they said the Core might be the source of energy they were looking for? Let's go with that, and have them fix the blasted ship already. Then you end up stranded on different planets, and yada yada.