Having too much blood or gory graphics isn't against the rules. As far as I know, it should be okay unless it's like actual bodies being used which would be pretty messed up. There are a lot of violent games here that are pretty graphic.
You can always clarify with a mod.
Mikoma
Were the submissions named "Duneon gunner" and "maze game thingy"?
It looks like those were taken down by the moderation team. I haven't played those submissions so I don't really know why they were taken down.
Read these to see if you have violated anything:
https://www.newgrounds.com/wiki/help-information/content-submission
https://www.newgrounds.com/wiki/help-information/terms-of-use/game-guidelines
If you want to ask a mod, then try to send a portal mod a PM. I'll link you a list here:
https://www.newgrounds.com/wiki/help-information/site-moderation
spookman204
now i think for dungeon gunner it might have been removed for maybe to much blood in the cover art, and bullet holes from one of the enemys, but i have no idea for "maze game thingy getting removed"