Just a quick heads up, the things you mentioned are already triggering alarm bells in the back of my head. "Isometric View", "Gamepad", "Inventory", and "Dialogue Trees" are all topics I wouldn't consider beginner material. On the other hand, there are significant amounts of existing resources like tutorials and examples available for these topics if you look for them.
You'll probably run into many of the same logical problems regardless of what engine or platform you decide to work with, though I have limited experience with others.
Try out the beginner tutorials first, and see if the way Construct's event and picking systems are structured make sense to you. Then if you get stuck on something specific you are trying to do but can't figure out or find a tutorial for then ask again on the forums and I'm sure someone will be able to point you in the right direction.