filteredSystem("activated", { activated = T.Entity }, function(e, _, system)
    local activated = e.activated
    if activated.addOnActivate then
        for _, toAdd in ipairs(activated.addOnActivate) do
            system.world:addEntity(toAdd)
        end
    end
    if activated.pickedUpOnClick and #HeldByCursor.entities == 0 then
        activated.placedOnClick = T.marker
        activated.moveWithCursor = T.marker
        activated.canBeCollidedBy = 0
        system.world:addEntity(activated)
    elseif activated.gridPosition then
        for _, held in pairs(HeldByCursor.entities) do
            held.placedOnClick = nil
            held.moveWithCursor = nil
            held.highlighted = nil
            held.canBeCollidedBy = CursorMask
            Replace(activated, held)
        end
    end
    system.world:removeEntity(e)
end)

Collisions = filteredSystem("collisionResolution", { collisionBetween = T.Collision }, function(e, _, system)
    local collidedInto, collider = e.collisionBetween[1], e.collisionBetween[2]
    if collider.highlightsCollided then
        if collidedInto.unhighlightSiblings then
            for sibling in pairs(collidedInto.unhighlightSiblings) do
                sibling.highlighted = nil
                sibling.canReceiveButtons = nil
                system.world:addEntity(sibling)
            end
        end
        if collidedInto.highlightOnMouseOver ~= nil then
            collidedInto.highlighted = T.marker
            collidedInto.canReceiveButtons = T.marker
            system.world:addEntity(collidedInto)
        end
        if MouseJustPressed(1, true) and collider.isCursor then
            system.world:addEntity({ activated = collidedInto })
        end
    end
    system.world:removeEntity(e)
end)