locked projectile pack&relays.
Oh sure, and every average blockland player can string events on the go to get that to work no problem.
Add-ons in general are never an absolute necessity, they don't need to be either. For instance, weapon add-ons, but wait we already have weapons so why do we need more? Hurf Durf could easily make that bouncy ray laser thing with events hurrr
The point is, it doesn't need to be necessary as long as it's a cool idea. I don't know about you but stationary blockland turrets you could set up around the place and knock over (bonus) would be pretty neat.
