old extension and have it replace the new file if you want to go back to regular HD Edition. The Backup is included as empires2_x2_p1.old, and all you do is remove the. This file goes into Program Files - Steam - Steam Apps - common - Age2HD - resources - _common - dat, and replaces the file. I have tested various civilizations, and I found some lacking, and others I mention here because I tested and did not decide to change anything yet.