The funny thing about game development from a one man team is that the first 80% is the easiest part of making a game. The last 20% includes 10x more testing, usability studies, gameplay tweaks, graphics updates, music selection, marketing, polishing, flame hoop jumping, sky diving, etc ... This last 20% is where all the other parts of making a game that is usually handled by other people creep up and needs more attention. This really detracts from making improvements to the code to make the game faster, leaner, and easier to update. Although it is the hardest phase of development, it is also the most fun part. It is at this stage where you start showing your game off to people to get their feedback into the game. This is also where you put the icing on the cake that really starts to make it look like it was developed with love rather than a collection of game ideas hoping to form a game. This also serves as a great accomplishment waypoint, where as when you first thought about your game, doubts about how the game will come out is high. Thinking if I will even have the passion to push through with this really hard endeavour. But I think this is really the first time you can deflate and relax, assuming things moved along to solidifying the core game mechanic of the game.
I'm in the last 20% of the game right now with Gum Drop. Now I have to gather feedback from multiple player demographics about the game. Not just asking them how the game is, but actually watching them behind their back and see how they interact with the game. Taking notes, in what works, what they don't understand. Of course listening to what they have to say is important too, but really just observing how they interact is the best way to get unfiltered response about the game.
The hardest part I have with the game right now is not actually the gameplay itself but the UI and menu design. I'm not really the best UI developer, or have the natural instincts to go with what works best. But I really have to sit down and start designing the HUD and the menu flows. Because this is how information is relayed to the player and it has to be precise and meaningful.
Other than that, development is chugging along. I took a 2 day break from working on the game to get my bearings back straight, too much game development can really take it's toll, and ultimately you stop having fun. Which is never a good thing :)