Every generation in every world has their heroes. Heroes represent the ‘best’ of us, with quotes around ‘best’ because what is considered to be ideal varies from culture to culture, from society to society. If you’re going to put a Hero’s Day into your game, you should consider using it to communicate an interesting or strange ideal of those who celebrate it.
Some ideals you could go with are athletic prowess, killing prowess, or dying while trying to accomplish something that the society wanted.
Some other ideals are a prejudice towards a people group, whether it be racial (actual races, like elf or dwarf), color-based (the real-world version of racial), cultural, religious, or rivals (from sports or enemy kingdoms). In this world, generally the fighting of prejudice is idealized, but, like I said before, we’re trying to go for strangeness.
You could always have the hero be what would be considered typical, but then make the actual celebration weird. Something wholly unexpected would be best, since it throws your players off-balance. But, if you want to do something boring and expectable, it still doesn’t hurt to throw in this holiday anyway, since it gives details and flavor for your setting.
If you come up with some other ideas to use with Hero’s Day, put them in the comments below.