Hi TurtleGhost. It is definitely allowed to have multiple levels in your game. We encourage you to make each level a self-contained, like a stand-alone 20 second game. If you are not carrying over items or abilities and your levels could be played in any order without it making a difference, then that's close enough to the spirit of the jam. Having a narrative that continues from level to level does make it more like a longer game played in 20 second installments. Having said that, we like to give advice about what we think is in the spirit of the jam but we accept all games that clearly engage with the 20 second constraint and we don't disqualify games for different interpretations.