For the most part I've just been coding my games in Javascript and Python (the latter using PyGame), but I also tried my hand at Ren'Py, and loved it. On the rare occasions that I used pixel art, The GIMP turned out to be surprisingly well-suited, if overkill. It was also useful for altering some 3rd-party art that didn't quite fit my needs, thanks to all those filters. But I've been trying out all kinds of other tools, for various purposes. It's always a good idea to be curious.