Does the rules say anything about gore (and what counts as gore?)??

probably as long as its not too graphic

I'd say it's probably fine, but do tread carefully since people could consider it to be a violation of this rule:

- Games submitted to the GMTK Jam must not contain nudity, or hateful language or visuals.

Depens on the gore, I'd say. Hotline Miami has been mentioned several times on the channel, so gore at that level is atleast allowed, I think

if gore on the level of hotline miami is allowed then you can essentially do no wrong :P

i wouldn't worry too much about it, it lists hateful visuals, and gore doesn't really fit that imo