I created a variant (it's really just a time control variant with standard rules) called "Deathclock". Each player gets a random amount of time within a specified range and the clocks of both players are hidden from both players. It's supposed to be like life...you don't know how much time you have but still have to manage it well. I have an live example running where you play against Stockfish (you get more time than Stockfish). I may set it up so that humans can play humans but wanted to see if there is any interest or if people think it could be fun.
deathclock.life/
deathclock.life/