Ty so much for the thorough feedback! Very helpful and super appreciated! Definitely planning to add a tutorial post jam, just ran out of time in the 3 day window :( I'll have to take some notes from your game b/c your tutorial was super well done!
And you're right about taking damage from hitting linked enemies on hard! I definitely overtuned the difficulty on that but figured I'd throw it in the jam build anyway just in case anyone was feeling masochistic haha!
So the skull thing makes it so that your chain multiplier won't reset bt/wn enemy waves. So you can use that to really boost your score if you manage to not get hit or shoot the connected enemies. It lasts for 30 seconds. I was gonna put an explanation on the page about it (and might add it to the tutorial when I get to that), but decided against it b/c I remember arcade games often having some obtuse mechanic that you had to figure out from either playing or hearing about it from your buddies so I was kinda trying to mimic that feeling. I may keep it out of the tutorial and just add some juice to try to make it easier to pick up on during gameplay.
Oh, and my wife did the music/sfx/and backstory and said she's super happy you enjoyed those!
Thanks again for playing and commenting! Glad you enjoyed and thanks for making an awesome entry yourself :D