It's not a platformer if you can't jump
Agreed, new parts aren't polished as it's pretty much incomplete. Half of the map wasn't ready and couple of NPCs are still missing to make it for a compelling level and my art sucks. It's too repetitive.
Key example is actually crucial. You're locked in a small room and you have no other way to progress other than finding a key and using it. I'd say it's a good design choice to have your player experiment with smaller, obvious puzzle as that prepares him to understand how to solve other interactions in similiar way. Having a quick use option for an item would just increase the 'z' spamming.
About these clues... please don't force me to make a Witcher sense... but! Looking back at Oblivion your crosshair was changing shape when in close proximity to usable item. I think it would be a good idea to have a little 'inspect', 'search', 'open' tooltips when next to interactible item. I'll look into it.
Strongest point of the game is my writing? Oh... oh no...