Make sure you have Elixir ~> 1.5.1 available. What about aging; could be a separate tick for everyone (easy) or some kind of "everything ages at the same time" tick. If the latter, I need, I think, to make it possible to subscribe to events in the ECS framework. Well, my "Watcher" idea is growing old quickly isn't it. Unless I create a Universe entity with a Tick component which could get updated with a monotonically increasing value, and that would be something that various things could watch...