Cool idea for a platformer, but it needs some polish.
For example- the game gets HARD on the second level. There are no hints where the platform will be in the "other" world, so I kept falling down and eventually quit.
The presentation was ok, the game felt like a nice old-school platformer and looked like it too.
Over all- I see this is your first jam! Good work on making your first jam game! Keep it up!