We've been invited to DD1's home to spend the evening with them. Her in-laws will also be there and will be bringing some games, apparently. We usually watch Big Ben and the fireworks on TV, then sing 'Auld Lang Syne'; sometimes we go outside if the weather permits to watch local fireworks and maybe bang a saucepan or two!
When our girls were small we used to have a party with neighbours who had children of a similar age, because none of us could get babysitters. The children could go to sleep upstairs (but rarely did!) and we played silly games we could all join in, like the Generation Game. Happy times!