The Humble Bundle became a massively popular way to buy collections of games as the price set by the purchaser. A portion of the purchase price goes towards charity with the rest split between the game developers. Humble Bundle continues to offer these limited-time bundles, but have expanded to include a persistent storefront. The Humble Bundle concept was initially run by Wolfire Games in 2010, but by its second bundle, the Humble Bundle company was spun out to manage the promotion, payments, and distribution of the bundles.
The Humble Store lets you choose from thousands of games for PC, Mac, Linux, and Android while supporting a charity of your choice.
Most games have the option for a Steam key where available and or direct download capability.