Ok, thanks for the video! I could easily fix the problem... I could add a block right above the other red locks-block, so that it would become too high to jump without the key. But I'm not fond of the idea of submitting a second version, with such a small modification. One thing I'll do, I'll change the topic's name from Hard to Very Hard, since everyone seems to agree on that. Well, except for me of course.
If someone has a better opinion of the level, please tell me about it
Anyway, at least one person had fun playing it, me.