Oh my gosh, thanks for all this helpful feedback!
I'm always really bad about adding sound. It always gets put last in my priority list, one because I work alone, and two, because I don't really enjoy scouring around for copyright free sound effects and music to add. But I may need to put more of a priority on it, because it seems to be important.
I do understand the issues you had with certain parts. I did intend on fixing a lot of those things, but I obviously ran out of time :(. I was very proud of the mode swapping animation, but I may have spent too much time on it.
For the top left spike puzzle, I will tell you that you need tank mode to cross the gap (but no, it can't drive on spikes), if you ever feel the desire to come back for some reason.
So, thanks for all the feedback, it means a lot!