Hello

I have... a few questions about this achievement. Is it possible to complete it in normal game, not 'rigging' it in your favor? Cause for now, it looks kinda hard, and there is not enough explanation - for example, does Cat's Paw on land units counts torwards restriction, or doesn't? 

Actualy... does anyone has tips at all? ^.^" I'm trying to get as much achievements in single play as I can, but I'm not going to kill myself for them. For now I'm good, but I wonder if I manage to survive, if 'someone' decides to invade me via land...

No Cat's Paws units will not impact getting the achievemnt.

For that one play islands and a difficulity or two down from where you nomally play. Make sure you have a strong Navy and never let any units make landfall by your cities.

Just go for an internal vicotry both scientific and eceonmic victories should be easy.