For the arts, definitely mastodon.art. For gaming, I couldn't find any good (uptime-wise, and English) instances for just gaming, but https://mastodon.gamedev.p

For the arts, definitely mastodon.art. For gaming, I couldn't find any good (uptime-wise, and English) instances for just gaming, but https://mastodon.gamedev.place https://mastodon.gamedev.place (gamedev) or https://boardgames.social https://boardgames.social (for the other kind of gaming) came up while I was looking. I used the list at https://instances.social https://instances.social.