Valhalla is a browser role-playing video game that immerses players into a medieval fantasy of Scandinavian mythology. All 9 worlds of the Great Tree Yggdrasil are now crowded with hostile creatures. You have to clear all worlds from enemies and restore the balance in the universe. The gameplay includes character development; harvesting, crafting, and buying equipment and materials; a branched storyline with repeatable quests, and many other features. Moreover, Valhalla has many ways of interactions between players: guild system, trading of NFT items, PVP arena, and in-game chats (personal, guild, and public).