i have made platform games with stencyl, stencyl is probably about the same for making platform games, it was last updated a month ago. I didn't do that here because that wasn't what i wanted. I am making another platform game now. the carrying of one object served as enough of an inventory for me.
about having a clear goal, i don't think that's really is what makes games appealing. I like games with clear goals, but i also like games that have no clear goal, those were the ones i was most inspired by initially, like Knytt Stories, mateusz skutnik's daymare town games, Nekra Psaria and An Untitled Story. I think it's less about goals and more about how the game guides your perception. But appealing to other people isn't my primary goal, so i don't know if i really want to think about that too much.
The one thing i completely agree with you on is including all 4 arrow keys when only 2 were used, i don't mean to be confusing about the controls like that. Clicking space would be based on the x and y coordinates because it doesn't make sense that you can interact with something when you're far away from it. I made the music, btw.
Thanks for the lengthy comment, it stimulated me to think about why i do this stuff and all the little details.