There are many, many open source reddit alternatives. Several of them fairly good. All mostly ignored. I think something built on the recently released Freenet

There are many, many open source reddit alternatives. Several of them fairly good. All mostly ignored. I think something built on the recently released Freenet 2 has a lot of promise. But it's all a popularity contest and that isn't about merit. The number one reason things are popular is because they were already popular or other social networking effects.