I've been fixing a LOT of things in the last two weeks, and there are still more to work on, hence Alpha19 will be delayed a little bit. The previous versions were a bit too unstable, so I think it's a good idea to take some more time and clean things up. Plus I'm in the process of moving to a new country, so I'll have to spend some time packing and unpacking those boxes. :) One serious bug that I'm pretty ashamed of concerned autosaves. By principle there should always be a recent autosave that can be used to recover the game after a crash (unless it's a new game). Because KeeperRL is a perma-death game, it deleted save files after they were loaded. Which included autosaves. So if the game crashed within 1500 turns of loading, it was completely lost. In the fix, regular save files are renamed to autosave files after being loaded, and files are only deleted after the game ends (when you win, lose or abandon it). This makes cheating a little bit easier, but it's a better alternative than players loosing their progress.
I spent a few days optimizing the rendering code, which brought about a 50% increase in frame rate in the early game. Later in the game other things take more of the CPU, so the improvement gets smaller. I'm planning to optimize gameplay code too, though, so hopefully everything will get faster. I've fixed lots of other bugs, including one that was almost a year old. On top of this, I'm still replacing parts of the code related to the recent move to SDL2. I've had to implement my own audio library on top of OpenAL and Vorbis, because anything I could find didn't work well enough. This is definitely a downside of not working with a game engine like Unity or Unreal. But when I'm finally done with this s**t, imagine all of that steam going into gameplay improvements. :) Right now I predict that Alpha19 will come out in about two weeks.