#units

The idea is to create a mod that would allow you to passively gain experience for land, sea and air units:wallbash: For land units, the training ground would be an improvement For the Navy - sea fort/naval academy For air units -training airfield/flying school A unit stationing on this...

When a new units get available it automatically replace the old in the city building menu. If I don't have the resources for the new units, the new unit get grayed out and the old stay available for some time until obsolete. This mechanic works great, so I wonder what is the idea/reason/purpose...