Gearbox teases another new game and we have no idea what it is

Yesterday, Gearbox teased a PAX East game reveal that is almost certainly—I mean, obviously it is, but I'm not supposed to say that because it's not official and all that—Borderlands 3. Today it teased another game, and this time, I am baffled.

We're all baffled, in fact. So far we have two working theories: It's an Aliens reboot and that's Lance Henriksen on the table, or it's Brothers in No-Arms. One thing to note is that Gearbox specified "another game" in the tweet, meaning that it's not Borderlands 3 (or whatever the mysterious highway sign game turns out to be), not that it looks like anything from that series anyway. It's also possible that this could be something brand new.   

Obviously we're open to other ideas, so feel free to contribute in the comments. The truth will be revealed at PAX East, which runs March 28-31. Assuming the mystery game (New theory: Bulletstorm 2, and that's Ishi finally getting fixed up) is revealed at the same time as not-officially-Borderlands 3, the beans will be spilled on the 28th.