-running, jumping or walking while using a shotgun kills you
I'm aware of this bug.
-pushable block under a normal block (instant kill) when grapping.
Not sure about this one. A screenshot or video will be helpful.
But keep in mind that working with the GameMaker engine is a MAJOR PIA for me (for more than one reason). These bugs, although serious, do not make the game unplayable, so I cannot guarantee that I'll fix them.