Besides default WC3 resources, I'm using:
- Icons from the indie RTS game 0 A.D. (which are available under a free license). Make sure you check it if you're interested in strategy games and ancient history and contribute in it's development if you have any suitable skills and time. It is currently in a playable alpha state.
- Icons, skins and models from WC3 modding sites The Hive Workshop, XGM.ru and Wc3C.net.
