Depends on what you are looking to achieve exactly.
Both open source projects and shared royalties can work, but making a full game is a huge endeavor either ways and chances of success are rather low.
You'd be best off starting out developing demos that can later be pulled for assets towards a complete game. As you build them and share them(or at least show them off) you are also building up a reputation that might help build confidence in others so that they might be more willing and interested in joining your project, whether open source or not.
But ultimately you have to be willing to see your project to the end yourself, if you lack that conviction then the project will not go anywhere even if you do get some contributors. It might progress for a little while but would ultimately just get stuck at the first big hurdle.
