Hello, long time chess player here! I've created a prototype for a chess variant I came up with called Secret King. The game is on my itch and the link is posted here: https://basmalord.itch.io/chess-secret-king

There's a description on the itch page, but in short it's basically chess but you and your opponent secretly pick a piece to be your king. There's no checks so you have to rely on your intuition and your opponent's strategy to correctly guess and take their king to win!

If you're interested, let me know what you think of the game in the comments on the itch page!