I was so impressed that my daughter Emily came up with this creative game all by herself that I had to share it with you! She invented a fishing game using her magnetic building blocks, a dressing gown belt and a hanger, and it was a huge hit with her brother Frankie! They played it for ages together and fed the pretend fish they had caught to their teddy bears.
You could also come up with a scoring system to add an element of competition and learning. e.g. 2 points for a triangle, 5 for a square, 10 for a hexagon. Or a colour based system would work too.
If you wanted to get even more creative you could use canes and some twine to make fishing rods and get them to decorate them with washi tape and stick on gems. Let me know if you give it a try and what your kids think of the game.