If you can't find someone you like, create your own post. In the post, mention following:

1. Your Game Details, Name and Page link.

2. What are the features that you expect in another game that will be complementary to yours?

3. What you used to make the game?

4. What can you use to work on the project? eg discord, repo  etc. Do not post your actual details in the post, share them with your partner directly.

If you found someone, mention following as reply to their post:

1. Your Game Details

2. Features your game can contribute to theirs

3. If you can work with them on the tools they have.