My elder son went through a chess-mad period, becoming the first grade 1 child to make the school team in South Africa and then playing for the Kent county juniors when we moved to the UK. He also made it to the national finals of the British Land UK Chess Challenge two or three times.
I was unable to bake the cake myself, because the oven in the house was not just temporary but temperamental! Sadly, the lady from whom I ordered the cake botched the order and handed over two rather lopsided square sponges. But there was no time to make alternative arrangements, so I did the best I could with what I had.
I bought black and white balloons, and black and white paper napkins. I couldn't get black paper cups, so had to settle for just white ones. The kids all dressed in black and/or white. As usual, I covered the table in tin foil, but instead of laying the food directly onto that (see note below), I laid out alternating black and white napkins and then placed the food on that. Surprisingly enough, I was able to find loads of eats that were black and/or white or an approximation thereof.
The two things that took the greatest effort were the cake and the bowls.
This is when I proved how really sad I can be. If you look carefully at the pic at the top of this post, you can spot the bowls on the right.
I cut strips of black and white card and wove them into a check pattern. I then cut diagonally into the corners and folded up the sides and secured them to make squared, chequered bowls. It took me several hours to do them all.
Of course, then you have to get creative with the games, since a mini chess tournament isn't likely to go over too well. You can use regular games and give them a bit of a twist (so that all progress has to be made knight-wise or bishop-wise)... or even just a new name. Most of the time, the kids wind up playing whatever they want, anyway, and you're only too happy to put your feet up.
Note about the tin foil thing
You may have noticed a recurring theme in the pics of my kids' birthday parties. Long before I got married and had kids, I learned a trick from the woman who organised all the council functions where I worked. She covered the tables with tin foil and then placed the food directly on that. And this included dollops of houmous and blobs of cream cheese drizzled with sweet chilli sauce. It looked great and it saved on the requirement for bowls and plates (and the need to wash said bowls and plates thereafter). Then, at the end of the function, she would just roll up the tin foil with the leftovers inside and bin the whole kit and caboodle.