If you hadn’t seen Handelabra has teased a new game https://twitter.com/handelabra/status/917809584324202497 which has this link http://handelabra.com/game3
This page is only a countdown though so we’ve got most of this month to speculate what they might be working on.
I might guess Spirit Island given its overall success...
The update did say odd choice; Spirit Island would actually make more sense.
I remember a year or two at one of the GenCon GTG Q&A's (say that ten times fast), it was said that Handelabra was interested in making Compounded into a game.
That could be interesting.
EDIT: Source I was referring to. https://youtu.be/ke3itOtL_9U?t=2466
Spirit Island would be a pretty involved adaptation, I would be surprised if it were ready so soon. I expect that “odd” has something to do with the game.
I'mma go out on a limb: Galactic Strike Force.
GSF would be an interesting choice, but I think there would need to be more public interest or a rerelease/v2.0 of the game in order to make it worthwhile.
It's always found it telling that I can buy Galactic Strike Force + Expansion + Minis on the GTG store for cheaper than buying just the base game from them (found that one out a few months ago when I was considering buying the game). That reads to me like they're trying to dump stock.
I’m pretty confident it’s not GtG related. I’m just not sure who else they’re working with.
Deck Building the Deck Building game maybe?
GSF would work better with some automation, though.
Don't get me wrong, I really like it. There's just a lot of moving parts
The Handelabra twitch page is hosting a stream by Penny Arcade playing One Deck Dungeon. If this isn’t the mystery new game they’re making then this is a terrible tease.
And it looks like you would be right, Powerhound.
And it looks like just the sort of game I'd have fun playing, which makes me happy.
We did say it was an ODD choice didn't we? 
The answer was there all along. How truly ODD
Yay for ODD!!! 
http://handelabra.com/onedeckdungeon/
I'm very excited for this! One Deck Dungeon is one of my favorite new games of the last year and a fantastic solitaire game. My only gripe with it is the bookkeeping aspect, so having a digital implemenation of it will be most excellent.
Fingers crossed for an iOS version as well as this would be an amazing game to play during breaks on my iPhone or on my iPad while multi-tasking.
Oh my GODD, you guys.
The Kickstarter project is live!
https://www.kickstarter.com/projects/handelabra/one-deck-dungeon-digital-tabletop-game
15% funding already.
I'll donate later today, once I'm home from work.
Just backed it - looks pretty fun :).