I'm demaking/porting Space Funeral for the GB, and I was wondering if it fit into the rules? My problem is that most of the assets would remain "unchanged" [basic recoloring of tiles to fit the gb pallete, and basic edits for actors] Platforming sections along with new assets for the sections would be added, but the base portion of the game would be the same.

Is this within the rules, or would all assets need to be redone in order to fit the jam rules? 

Thanks in advance.

Is this your own game you've previously written for another platform, or is it a game where someone else has rights to the assets? (i.e. is there permission to just re-color and re-use the tiles?)

For the most part, it seems covered by this part of the rules:

https://gbdev.io/gbcompo21/

Asset packs for art and music are ok if the licensing permits. Be sure to make note of what is being reused and under what terms. Use of pre-made assets (vs original ones) may be factored in when judges assess points for relevant criteria (e.g. graphics, audio).