Check out our indexing guide here, specifically the section on search: https://itch.io/docs/creators/getting-indexed#limitations-of-search
Generally speaking, it’s not worth trying to optimize for “topic” queries on our text search engine. It’s rare that people utilize the search bar for that, they instead use the search bar to find something by the name. If you want people to organically discover your project then we recommend using the appropriate tags and metadata.