Levels 1-3 are now fully mapped, level 4 is part way through the mapping stage. The tileset for level 5 is complete, so I need to work out the overall structure of the level before starting to map it out.
The main progress has been enemies - I've coded a new bunch of enemies and have now populated the first 3 levels entirely. This gives me the first real glimpse of how the game truly plays and it's now a matter or balancing.
Difficulty is a hard thing to judge, especially when you're the author of a game. But for the most part I can see where the especially challenging (or potentially unfair) bits are, and also get a feel of how many hit points the player should have. I've still not locked down the overall structure...my current plans are to have each level quite challenging, but also implement an autosave feature meaning you don't have to wade through the same stages every time you play.
This is a fair option if I can add a sufficiently large number of levels to stop the game feeling too short. If not, I may have to return to the more traditional style, but maybe with a lot (or even infinite) continues with every play. Limiting continues is only something I would do with an overall easier game, but it does make the balance a lot harder to reach.
Alternatively, I could just add levels of difficulty based on player health. That may be the best route, although I have considered a hard setting that has additional enemies, for those who really want to push themselves.
Another thing I implemented is a simple player death animation which pushes you back to the map screen. I have come across a bug on occasion which I'm not sure if I've fixed, so it may be time soon to get external playtesters. There's also a minor jumping bug that happens rarely, but is easily reproducible. This one has me a bit stumped. Bugs like this are especially difficult when you're someone like me who isn't really a dedicated programmer, but I'm sure it will all sort itself out in the end.