>>536328534
The game itself can't be "trademarked". Trademark protection only applies to trademarks, which are the symbols used to identify a product with a brand. Most notable are the title and logo of the game, but depending on jurisdiction, such protections could extend to any number of aspects which could reasonably be argued to constitute the game's brand identity. These protections exist so that unrelated 3rd parties cannot damage a brand's image by trying to pass off their own products as being officially made by them.
Under US law specifically, trademark infringement requires that the infringing party's behaviour could cause a reasonable consumer to confuse their product with that of the trademark-holder. In this instance, as long as you clearly and consistently advertise a fanwork as not being approved by Kit9 Studio, it is unlikely to cause such confusion, so you would likely not be infringing on any trademark. Copyright still applies, of course, and your work would likely still infringe on that, however.