Users used to be able to mark submissions themselves but it was being abused or misused with absurd frequency so we limited the option to staff. If you feel something should be marked, feel free to mention it on the submission notes and a staff member will mark it for you.
As for what qualifies, sexual content and extreme violence or gore are what we look for. Mild blood is fine and suggestive content is too as long as it’s not explicit but sex acts and full nudity, for instance, would be marked and very violent imagery or significant gore (e.g. dismemberment, massive amounts of blood, depictions of self-harm, etc.) would qualify on the non-sexual end. It’s also worth noting that while nudity and even sex, as long as it is not overly graphic, are permitted, it must be relevant to the game. Pornographic games are not permitted at all so if the game is more sex than gameplay, it won’t be accepted regardless of marking.
As for what qualifies, sexual content and extreme violence or gore are what we look for. Mild blood is fine and suggestive content is too as long as it’s not explicit but sex acts and full nudity, for instance, would be marked and very violent imagery or significant gore (e.g. dismemberment, massive amounts of blood, depictions of self-harm, etc.) would qualify on the non-sexual end. It’s also worth noting that while nudity and even sex, as long as it is not overly graphic, are permitted, it must be relevant to the game. Pornographic games are not permitted at all so if the game is more sex than gameplay, it won’t be accepted regardless of marking.