There are many multi-player variants which take advantage of the fact that the go rules generalize easily to multiple colors. But when playing with more than 2 players, there are lots of new complications (how to define objectives? how much diplomacy to allow?). Here’s a variant which combines the fun of multiple colors with the simplicity of 2 players:
Before starting, place some number of neutral stones on the board. Then play normally with black and white. No more neutral stones are placed throughout the game, but the stones already on the board behave just like they would in a 3-player game (for instance, they are removed from the board once they run out of liberties).
Unlike the last variant I proposed (Playing on the union of two boards), this is super convenient to play on VGS. One of the players takes the seat of the blue player to place some predetermined stones (while black and white pass). Once all the blue stones are placed, blue resigns the game. Then black and white can continue playing normally, without having to worry about passing for blue.
Here’s an example game I played against myself: https://go.kahv.io/#2488 (not the highest quality moves, just a proof of concept).
There are many fun starting positions to try out. I think a nice one to start with would be 5 blue stones on the star points of a 13x13 board. This will make corner joseki quite interesting!
If you’d like to try it out with me, just take the black seat in this game: https://go.kahv.io/#2505 (or feel free to propose your own starting position, with handicap if you prefer).
(Edit: That seat is now taken, just let me know if you’d like to play as well, and we’ll start a new board!)