Chesses

If you are looking for a 'causal' alternative to chess, then try the 'Chesses' suite of games at https://pippinbarr.github.io/chesses/ There are a number of variants here including 'Gravity Chess' which was featured on a number of recent tech sites. There is no AI for any of the games, so to try them out, you need to play yourself. As part of the fun is discovering the rules yourself, I won't spoil it too much for you, but I will admit to winning/losing a game of 'Chance' in one move! (Hint: 1.e4 is a dangerous move for white)