honestly I didnt use the shield to defeat the boss nor to unlock the jetpack basically what you need is the gem gravity fully upgraded and then learn how to basically infinitely make the boss puke gems out. it's really not that hard if you can be in about the middle of him before you hit attack and send him into puke mood it's pretty easy to hold to the right land on the ladder hit both tentacles again and repeat.
only problem is it doesnt save ur best like i left the game to check out something than came back to better my score on runaway and all my percents were erased. :/
graphics are good,
but i agree you messed up the game in general its pretty much impossible to finish a surgery first time around.
and it feels way too rushed.