IMHO, these teasers provide plenty of hints about the game.
The "obvious" ones include:
Steam whistle sounds;----A change in game sounds maybe, as was heard at CCC 2016?
"...prepare to take flight!"--- A shooting game of sorts.
Canopy over the "crew" in posters.--- Netting around the field again, like in 2013.
In
Steamworks promo video, starting at 0:51, you can see football like objects starting a circular trajectory, but stopping before they complete their path, as though they land in a "target". BTW, if you look carefully, the top of the "Top-hat" is open, providing a perfect target!
The posters also show ramps and platforms, reminiscent of many games in the past.
Morse code ringtone 3 in DLC pack 2 seems to translate to "The game is afoot"---I truely hope this is an indication we may be using football like game objects!!!