It is the ultimate in corperate gaming. They made this game and you pay for the characters. Yep (and although that sounds snarky, I applaud both the company for having such a cool idea and the company for sucking more money out of just one product)
You can buy the game and play but it also has a "tablet or stand" with 4 or 5 small coaster like pads on it that you can put characters you buy on them and they show up in the game.
For example, you buy the Marvel add on, you can buy the Dr. Strange figure, place that on the tablet and Dr Strange will now be a playable character.
Look
HERE