Starting off the multiplayer seemed to work well, had a friend join and we had no issues joining or any connection issues, and creating a online multiplayer game for a jam is crazy ambitious but you guys nailed it on that end.
My biggest issue is personally, I just hate that you cant move while shooting, this may be better with a higher pop lobby, but with just two people it just feels very annoying more than anything, again I can understand if it feels different with a lot more people so take that with a grain of salt.
The gameplay loop is simple and easy enough to get the hang of quickly, I can definitely see the Agar.io influence in it. I get the whole risk and reward of it all of it but I didn't feel like there was enough of a difference between having a higher goop count and a lower one where as in a game like Agar.io the difference is night and day. Since your attacks seemed to be limited to a max of 5 goops having more didnt seem super beneficial besides having more chances to heal/attack but I never really felt like I was running out of goops super quick. Lastly I think the base speed should be a bit faster cause even starting out you feel pretty slow.
The visual style is great, I think the game looks beautiful and you guys absolutely nailed it on the pixel art end of things. Not really much to add there I just loved it.
And with the theme I can understand where you're going with it but I don't think it completely matches the theme completely since it is within your ability to just not sacrifice the goops, and I think for the theme things should be forced. But I still think this is a really cool entry.