http://www.pcgamer.com/one-of-the-binding-of-isaacs-most-popular-mod-teams-is-moving-on-because-of-broken-mod-support/

Team Alpha, makers of the popular Alphabirth mod packs for The Binding of Isaac: Afterbirth+ DLC, is halting its work on the game because of a "broken" mod API and the failure of developer Nicalis to work with the modding community.

The team's head coordinator said the long-awaited developer tools released alongside Afterbirth+ in January were a "disappointment", adding that the expansion seemed "less like a tool to let Isaac live on through creators, and more like a last-ditch DLC to get some more cash out of Isaac before it was finally killed".