Each Secret Series Seed offers a short series (i.e., campaign setting) for you to run/play. These series will be extremely eccentric; while they still fit into the 1980s action cartoon mold, you'll find them to be very unique and strange.
Just include the amount indicated on the Add-On(s) that you want to your pledge amount. When we send out the big survey well after the Kickstarter has ended, you will have to list the Add-On(s) you selected.
Don't see the answer to your question? Ask the project creator directly.