Thanks for playing our game to the end, very much appreciated. Yes, it does crash right at the end as you go through the portal. It was one of the last bugs we didn't manage to fix in the post jam 2 day bug fixing period. It's a shame because that's where stats about how many deaths you had and how many biscuits you retrieved would have been shown and also where our online leader board as supposed to be. Doh!
There were 7 biscuits and we show them all in the YouTube play through video we added to the page. You might have missed the one right at the end that is behind the portal. Our artist and level designer Dan loves to put in those curve balls, expecting you to be focused on the shiny thing in front of you and not noticing the small archway in the distance hiding the last biscuit.
Sorry about the full screen thing. We did have Unity's default full screen button support but we found that sometimes it wouldn't go into full screen properly or come out of full screen properly. It happened often enough that we tried to hide it behind the itch.io full screen button (which isn't really full screen as you saw). It might have been because we decided to go bleeding edge and use Unity 6.3 alpha (my bad).
The multiplayer was a real stretch goal and nearly broke single player, but we'd not done any multiplayer before and we wanted to dabble with it for this jam. It was a real learning curve in how state is sent over the network and shared between clients and what works cleanly and what was a real pain in the "engine" (FishNet does not like you reparenting things it seems).
Thanks for all your feedback and for playing so much of the content we made for jam. Hope you've had a good one.