The latest Humble Weekly Bundle is all about playing together.
Pay what you want for Shadow Puppeteer, Ibb & Obb and Hero Siege.
Pay above the average price for Hammerwatch and Damned.
Pay $10 or more for Forced and Contagion.
All games bar Hammerwatch are redeemed through Steam only. There are a few Mac and Linux ports there, but it’s mostly PC.
As ever, you decide how your money is split between developers, organisers and charity.