Today marks the release of the PC version of Disney Infinity 3.0 on PC. You can get the free download from the official website, Steam, or the Windows Store (if you're using Windows 10).
The PC game features the same full experience that you get in the console editions except that it does not use a base, you instead either buy characters digitally or you use the webcodes that come with the figures to unlock them.
You can still play the PC version even if you don't own anything, the game has a weekly rotating selection of characters that it'll let you try out. And if you're still after free characters you could try the Rewards program they're running where for every 10 friends you recruit you get a free character.
Additional features for the PC version over the console versions include Quests that you can complete to earn in-game rewards, a Daily Challenge (which is essentially just a round of the Hero Destroyer from Toy Box Takeover), and the ability to play demos of the Play Sets or Toy Box Expansions you don't already own.
The game is full to the brim with micro-transactions so be careful what you click on.
The systems requirements, as seen on the official website, are as follows: