I found some strategies to beat Gutmans stage (aka the whole demo) easier.
1: For the moving platform section, instead of jumping manually which is hard to do every time the moving platform flips, go onto the little square thingy's on the side and you shouldn't fall down.
Also the for some reason the whole platform doesn't flip down, so the very back of the platform will be safe to stand on, if you hang out in the very back you wont fall down.
2: Pickelman, (the guys who have shields and the guys who throw hammers) are hard to kill, so i found a way to kill them in a very easy way.
Just keep moving from side to side while shooting and you should kill them easier.
3: A way you can beat Gutsman, is to just move from side to side while shooting, kinda like killing a Pickelman, but jump if nessasary.