An alternate version of the military campaign, all of the scenarios are playteseted and are all passable on Normal difficulty, (some of them are not passable in very hard , so if you like challanges go for it :).
You can find walkthroughs of the campaign here:
https://www.youtube.com/playlist?list=PLxgqYwsObQ4UmEXepFkhLQ2G0WZwDh302
Hope you enjoy :)
Note: There are three versions of the 15th mission all of them are pretty much equivalent in difficulty.