Well.... Superpowers is considered "completed" project and is kinda usable, however the HTML5/Browser environment is ever-changing what works today may generate error tomorrow.....
The real benefit is that it's fully open sourced, so anyone can pick and fork it to fix up a working version if you wish. If Superpowers has a chance to go Steam, will drastically make it alive again, but it really depends on the devs. Currently, they're just too busy to to this.