The sale was set up by Fugl developer Johan Gjestland, and a portion of the revenue from participating games will be donated to "organizations like Greenpeace, World Land Trust and The Nature Conservatory."
Two games are offering additional donations. During the sale, 15 percent of Subnautica's profits will be donated to The Ocean Cleanup, an organization which is devising technology to capture and remove ocean plastics, and One Tree Planted will plant one tree for each copy of Playne sold.
The sale runs until 4 pm Pacific on June 7, and you can find all of the participating games here.
Since I have a moment with the topic, and without suggesting that this is a sufficient salve to all our interlocking global crises, I also recommend composting, gardening along permaculture principles, and sharing food with your community if you can. I'm going to go water my plants now.