These days I've finished defining my current plans for the test build version of the game: it will contain the challenges mode (which will include a beginning, 15 levels and an ending), so people can help me test things out and also serve as a demo to check how the game plays, while hopefully being a fun stand-alone gaming experience in itself. The story mode will only be included in the commercial version of the game.
I still have some things to do before I finish and publish the first content complete test build. The beginning of the challenges mode and levels 1 to 12 and 15 are done, although some need more testing, I'm almost finished with level 13 and I also have a working version of the normal ending (I may add a special ending for those who finish with a 100% score in all levels, but it won't be in the next version [UPDATE: I've started working on it and it'll be probably be ready for the next build]) but still have to fully design and build level 14.
After that, I'll start working on the story mode. I'll probably update the test build with bug fixes, level tweaks and maybe some content updates but my focus will be on building the commercial version from then on.
As progress goes, I don't want to show too much of the levels I've added lately to avoid spoiling experiencing them for the first time, but there are some new small gameplay details I'd like to share, like the interactive safes:
and the changes to the lockpicking minigame (it's now more similar to the one in Skyrim or Dying Light, which I think fits better with what I need from it gameplay-wise):