Cat units for the Athenians! (There's the crazy story about the Persians releasing cats on the battlefield of Pelusium, knowing the Egyptians wouldn't risk to hurt them with their arrows).

I think this would promote self-destroying things, which I think is an extremely unsightly exploit  (that's why AI makes everything collapse), and as someone mentioned, one would want it "not to be too simple and rewarding". That's why other things were proposed, but maybe are a bit harder to implement 

Thanks exellent news! Your are right - the GUI is a bit "fiddly" and appears overloaded will have a careful look and try and imporve. Used it to convert very nice older skirmish and scenario maps already that I was missing 

Tried to implement this as a mod. Activating the recover-resouces mod below, the following applies onto entities you have constructed yourself and that are not under enemy capturing nor were captured by yourself: Whenever you self-destroy your finished buildings Whenever you self-destroy your finished siege engines Whenever you self-destroy your finished ship when it is near your dock (default 30m) you are getting back a fixed percentage of the construction cost (currently defined 50% as a default but the parameter can certainly be tuned . Note: the mod should work for both R0.28 and R.029 SVN. Please try and let me know if it works for you as well and what best parameters (percentage and ship distance to dock) you would recomment!   recover-resources.zip README.md

Just ran it on macos, it worked, though I didn't really try anything. The gui is pretty small, could you make it bigger please