I mean, we've all had ideas for PbtA or FitD or Belonging Outside Belonging or Lasers & Feelings hacks, but there's tons of systems out there that don't have a thousand hacks to their names. What are some of the ones you wish would get hacked a little more often, or at all? Here's mine: 

- Psi*Run: I think interesting things could be done with the Risk Sheet! There's an alternative universe where this, and not PbtA, became the Big Indie Hacking Phenomenon, and I want a peek into that universe. 

- Downfall: I'm biased because I've hacked it. As an engine for telling sad stories about inevitable doom, it's calibrated to perfection. 

- Questlandia: I've only read the book and listened to an actual play of Noirlandia, and it looks like it'd be long and involved to hack (not unlike at least one popular engine I can think of), but I think it'd be cool to see! 

- The Quiet Year: I wonder what a full-fledged hack of this would look like. Lots of list-making, for sure. 

I'm still surprised that A Penny For My Thoughts didn't inspire a big wave of imitators and hacks of the game for different genres. It does some really interesting, effective stuff with how to structure the storytelling and how to evoke a specific atmosphere through mechanics. If nothing else, the "ask two people what happens, then choose one answer to be true" thing could easily be used in many other games.

I'd love to see Ganakagok applied to other genres. I think it's core mechanics and concepts would be great when applied to things from space opera to alien abductions. The use of Tarot-like cards in that game is really smart, and could be used in almost any genre (basically, the dice mechanics use aspects of your character and the setting to decide who gets to interpret the Tarot-like card).

I like how Swords Without Master structures the game as conversation into specific phases and decides who says what when and how the tone dice work. But I hate swords and sorcery as a genre. So I would love to see it applied to other genres. Maybe even tell different sorts of stories. (I think you could use this over-the-top action adventure game to tell some interesting personal drama stories, but it would take some hacking to get there.)

I'm still figuring out what I want to to list here but as I'm reading this topic. I noticed that the following hacks exist: 

The Quiet Year has a hack called Looming. There's a podcast by the designer playing it: Atlas of the UNknown World. It combines Quiet Year, Spindlewheel, and darker outcomes. 

For Psi*Run, I made one very recently called  No Crime But Living: Fleeing Facist Wizards in a Modern Magical Society. It's pretty dark because it's supposed to be about the experience of disenfranchised people and also still under construction but I think it has potential.

Oh, I know the ones  I want hacked the most.

Over The Edge both the old ones and the new ones. I lvoe the flexible and background focused and it's very flexible. 

Unknown Armies I think there is a lot of potential from the madness meters and the way it handles that stuff. 

Puppetland it's diceless but I love core mechanic of what you can and can't do and the slow fading of your character when you get injured or act outside your nature. You literally have a drawing of your character and black out a piece of the drawing each time. 

But most of all: Hot Guys Making Out I love the core resolution mechanics and how it has what your character is "good at" and "able to do" and the difficulty acting outside of your roles.

I guess Savage Worlds? It's been a long long time since I've seen a change made to the core rules that felt energizing and fresh. The system takes small tweaks and changes for settings very well, but to me a "hack" is running with the basic mechanics until you get somewhere else (but I allow that maybe I don't understand the term fully). The only examples I can think of are the superhero rules for Necessary Evil and the dueling rules for Deadlands.

Technoir — the dice system is seriously brilliant, but the game got overshadowed by other bigger indie hits dropping at around the same time.