Cute and gory is already fairly established as a theme I think.
Looking at the characters I think they should all have individual melee attacks that match their species.
Obviously this would be something for later as it would involve a lot more anims.
Environments are something you have a free hand for being cartoony, unless you maybe pick an overall wilderness theme.
However a wilderness can encompass farms and the buildings and machines with it
Many creatures make their homes inside trees so you could do an Ewok village kinda vibe including walkways, ladders and vines.
A classic corridors map could use the theme of a bears cave complex.
I am also thinking that the fox would very much like a "catch the chicken" match set around a farm ;)
Melee attacks are definitely on the Todo list :D I had envisioned some super cartoonish crazy chainsaw that can be used in exchange for stamina.
Level Design I think will be the next logical step after getting the core function of the weapon loadout / ammunition pickups and random ammunition spawns.
I think I posted the Trello for this project on the main page. I didn't really think about setting up any place for folks to chat on it. We will see if many people download it etc :D
I was thinking the first 'Real' level would be something like a barnyard that would offer haybales and the barn and other things from a barn for obstacles to hide / and use for tactical advantage etc.
I think maybe having a "tag" game mode might be something I would like to work on in the future as well (taking in your last comment)