OK, I finally uploaded a video of my playthrough, it can be found here:

Don't get it... doesn't seem to have a goal either. 

I don't really get it. What should I do?

Produces this error upon launch and  does not run:

############################################################################################
FATAL ERROR in
action number 1
of Draw Event
for object grass:

Fatal Error: Can not create vertex buffer of size 589824 bytes
1363 vertex buffers allocated with total size of 784768 KB
at gml_Object_grass_Draw_0
############################################################################################