There is no catch. The developers all obviously expect a bit more than 1 penny for their games, but at the end of the day, you are allowed to set the price. Of course, since these games are delivered to you via download, they can sell the games at any price and still make a reasonable profit, since no actual manufacturing has gone into them (i.e. no cds / dvds were made). It's one perk of the digital marketplace; you can make a product and simply copy and sell it as many times as you want without incurring a cost (save for the bandwidth costs, which are usually very low).
You can even split the amount you pay four ways, between the developers, the Electronic Freedom Foundation (EFF), the charity Child's Play, and a tip for the Humble Bundle organization that sets up the bundles.
You can even split the amount you pay four ways, between the developers, the Electronic Freedom Foundation (EFF), the charity Child's Play, and a tip for the Humble Bundle organization that sets up the bundles.
