I run Game Courier, which is about as old as BrainKing. It is part of the Chess Variant Pages, which I also run, and it can be found at this address:

https://www.chessvariants.com/play/pbm/


Like BrainKing, it lets you play many games online with other members, but it also has its differences, and I will list some below:

1. It is run as a hobby instead of as a business and has always been free to use.
2. It supports many more games than BrainKing. While BrainKing supports over 100 games, Game Courier supports over 1500. However, most of these are Chess variants rather than other abstract strategy board games.
3. Instead of requiring me to program every game it supports, Game Courier lets users add support for new games. They may write code for new games with Game Courier's own programming language, or they may create dumb presets that do not enforce any rules.
4. There is also now a wizard that will generate code for new games, allowing non-programmers to add full support for new games, at least as long as they are Chess Variants whose rules aren't too different from Chess.
5. Games that are programmed for it, which should include any wizard-programmed game, will display legal moves.
6. It offers very customizable graphics, including multiple piece sets, multiple board images, and the ability to change the colors and fonts of auto-generated boards.
7. It is still in development, and I have no plans to shut it down soon.