Web version
I got really confused not being able to push mine cart *Am I pushing it from wrong side somehow?*. Most people will figure it out but some will drop it and send you a bug report. Showing that you have to have momentum may not be enough here, if you show it some players won't realize anyway, so show + explanation may be needed.
Played first time ever, here are stats:
Game time: 38:33
Deaths: 39 (some are from testing but only a few)
Map completion: 78.1%
Books: 14/16
Longest solve time: 5:38 (Bat Country)
Most deaths: 9 (Bat Country)
On first try gave up on level below AGDG room, booted game again and figured I could place Ice block how i want but I would say it was the hardest one for me. Bat cave took more time/tires but prob because it has more options to consider so amount of time and deaths may not be the best metric to see what's most difficult, instead it shows what's most complex.