The Journeyman Project games are some of my absolute favorites of all time and I'm thrilled to see GOG bring Buried In Time (my favorite of the three) on to the service.
The game features tremendous writing, a wonderful soundtrack, and some really top-notch adventure gameplay.
Even though this is the 2nd in a series, you don't need to play the first game to enjoy it. The only relevant information from the first one is that your character is a time travel agent who saved history and became a worldwide hero.
This is the sort of game this site was made for, and the price is a steal. Highly recommended!