If you have a fresh installation from Steam, you likely have a version 1.6+ (AE) build. To revert to 1.5.97.0, you can follow these primary methods: Guide :: Downgrade To 1.5.97 - Steam Community
If you have a fresh installation from Steam, you likely have a version 1.6+ (AE) build. To revert to 1.5.97.0, you can follow these primary methods: Guide :: Downgrade To 1.5.97 - Steam Community