So I was trying to make an obstacle for my game ,but even if I have selected the PNG format and have already chosen a transparent background ,the characters still hit on the transparent sides rather than the actual obstacle I drew (I allied the obstacle to the center )What can I do to solve this issue?
You need to update your collision mask on your sprite object.
The engine doesnt care what size the sprite is nor whther there is transparency. The collision mask has to be manually adjusted.
You can access the collision mask editor by double clicking the sprite object from the object list, then clicking the collision mask button at the bottom of the window.