At this time, it is perfectly possible to write modules. And even to distribute them to people, to play in their copy of Incursion (as long as its the same version it was compiled with).
Problems that need to be overcome:
- There is a nominal amount of hard-coded Hall of the Goblin King code in the game engine. This needs to be removed, but is not a big deal.
- At this time we cannot distribute a version of the game which allows module compilation. The original plan was to do so. But it's not possible, because the script compiler contains GPL code, as the compiler compiler that was used to make it, is GPL and has a small "runtime" that is GPL licensed. This means we cannot distribute binaries with this code in it, as the GPL does not allow it. People who want to develop modules need to compile the source themselves. This is the price we pay for using GPL code.
- The Incursion engine as is, only has roguelike area generation. You start in the top level, and you descend, and difficulty is scaled as you do. A module defines areas, and pieces that will appear in the given area, but allows little control over how and where they are placed.
So, you can make a fantasy D20 module in a dungeon that goes down, where the difficulty scales as you do. But you only get procedurally generated dungeons with mild coherence. If you're looking to create a sculpted adventure, you're in the wrong place. It is after all a roguelike engine, and the game it currently offers is a roguelike game.
It's an unfinished engine. There's unused and unfinished support for quests, an overworld, multiple players, and more.. in general an open world fantasy D20 adventure. But to make something more than HotGK it needs someone willing to program in both C++ and IncursionScript. And to be honest, if the goal is to make an ASCII open world D20 fantasy roguelike, someone who was willing to do so would be hard pushed to find something better than Incursion.