It seems that when AH inventions/war tactics/etc show up in someone's TL, they are one (or several) of these four things:
-Something from OTL, but earlier
-A combination of certain things from OTL
-Something from OTL, modified
-Something considered IOTL but rejected/cancelled
Maybe I haven't read around enough, but honestly, I'd like to see something totally unthought of and unheard of IOTL. A new invention, government system, or battle tactic; something completely original. I'm absolutely positive humanity has not discovered every corner of possibility, and I know many of you are really creative. So I'd like to see something, anything, that is a totally original idea.
I guess you could consider this as me daring you to flex your creative muscles. So I'll create some criteria for an example challenge. Here is said challenge, and (should you accept it) its criteria:
In 1916, have something that can be used to:
-Climb over trenches
-Be able to travel through rough terrain
-Be able to support infantry
-Bypass barbed wire/fortifications/trenches
And it can NOT be a tank.