It's pretty easy actually.

From the main menu, go to the custom screen, and then go to the 'Explore' screen.



By shooting up, the Steam browser will appear showing the levels shared by the community.

To download one of these levels, you need to click on the level and hit the 'Subscribe' button. This will let Steam know that you want to play that level and Steam will start downloading it to your computer.

Originally posted by author:

Note: We have uploaded a couple of the original levels as templates, so creators can understand the structure of a level.

Then you go to the 'Community Levels' screen and if you go up, you will find all the levels you've subscribed to.



If you like one level, you should rate it and leave a positive comment to the creator. It's always a nice detail.

Note: If, after subscribing and downloading one level, it doesn't appear in your Community Levels Screen, you need to restart the game and then you'll find it. It shouldn't happen, but just in case.

Note 2: To unsubscribe from one level, you will need to go to the 64.0's Steam Workshop Portal and hit the 'Unsubscribe' button.