The cultist wasn't necessarily a icon for the game but I liked it so much I just kept putting it as logos for things. Including these items. 

https://soundzydev.creator-spring.com/listing/cultist-design?product=2

Are you or a friend not the brightest? Well I've got the perfect items for you! All the items have a neat testing dummy logo as well as the testing dummy hashtag, #testingdummy. 

https://soundzydev.creator-spring.com/listing/testingdummy?product=369