The official free game is from the official website of the Chernobyl power plant.

Escape from Chernobyl is an adventure with puzzle elements that will have you thinking and make you wonder. The puzzle will keep you busy and your brain will be sharp as you unravel the mystery. And, of course, you will have to decide what to do and who to save. It's not just a game. It's a real-life story and a very important one. The story of a great team of scientists, a madman, and a few other people who decided to change the course of history.