If you are looking for variety, you could potentially add mousepads, key rings (in the shape of symbols, the logo, character emblems, etc.), flags (of the factions in the game), game posters, bed sheets, eiderdowns, pens and other artwork materials, gaming chair capes, carpets, towels, dishes (black dishes with the logo in the middle, sounds great), magnets (for putting in metal surfaces, such as a fridge), flipflops, plantpots, adhesives (for different kinds of places), animated wallpapers, backpacks, toys, and...
When you are finally ready, cosplay items.
If you are looking for creative associations, you can use not just symbols, logos and emblems but also the weapons in the game, the various races and classes, especial clothing they use (such as the Lich's crown), phrases from the game, and collectibles of the various factions.
Thanks! We put the store together pretty quickly but will see if we can add these items to it.Hats with the logo would prob be a good idea. I see many merch stores that sell hats