Some of my favorite communities that are fun and active are:

• !bicycles@lemmy.ca
• !cyberpunk@lemmy.villa-straylight.social
• !foss@beehaw.org
• !games@sh.itjust.works
• !linux_gaming@lemmy.ml
• !steamdeck@sopuli.xyz
• !technology@lemmy.world

r/RedditAlternatives is another one that might be worth mentioning instances on.

They provide games to claim each week as part of the paid Amazon Prime subscription. So they are “free” if you already have another reason to have Prime.