So I frequently like to pair the iBuffalo SFC-style gamepad with retro games of this sort of nature. Though it's more than blatantly obvious that the developers of this game -- like so many other modern retro style games -- expect everyone to be using the exceptionally non-retro style (and similarly just as non-retro friendly) Xbox 360 gamepad. One problem I ran into right off: it won't recognize my d-pad. As far as I can guess, this is possibly because the d-pad on many controllers like the 360 controller is actually mapped to the POV hat rather than x/y coordinates that have been standard for the decades before controllers like the 360 gamepad became the official unofficial standard for these sorts of games (once again despite how unfriendly it is towards these sorts of games...) This controller went with the standard instead and the d-pad just shows up as normal directions. Turning off the "use d-pad for movement" option didn't fix this unfortunately. So for now I'm forced just to use JoyToKey which I can't even say how much I hate being forced to use just to play a game with a standard gamepad that doesn't even need or use drivers or how tired I am of so many modern games requiring it (especially those that insist on using Xinput even though it lacks compatibility with the greater majority of input devices out there.) I presume if I could figure out what values to put in the config.json file I could manually configure it but I have no clue how to figure out what to put in there for the directionals. It's more than just a bit of a pain to have to manually edit a configuration file for your controls anyway... A simple solution here I suppose is to let the user configure which things act as the movement buttons -- though I still think it should be able to accept the X and Y axis as being, well, the X and Y axis...

I also found out that the only way to actually remove any configured buttons is to edit that file and put in nulls for those controls. Tere is no revert and no remove. If you accidentally duplicate something it's permanent. For instance, I accidentally set roll and map to the same button. Since I don't have enough buttons to keep each separate (and I'm used to things like maps being accessible through the menus anyway -- not sure why it isn't really) there was literally no way to fix this.

Another thing I figured out very very quickly into the game: there should not be a use button. It's silly to have a separate button that does this. Just have the up direction be use. In fact, I keep hitting up for things like opening doors without thinking about it and have to stop and willfully press the actual use button. Which brings me to another strange thing: the up for some reason jumps. Even if you're using the keyboard this is terribly awkward I assure you. Even back in the MS-DOS gaming days when I didn't have anything but a simple Gravis gamepad with only four buttons (all they could have before they went away from the old 2+2 system) and usually used the keyboard on games like these I tended to have a proper jump button and never the up key. (Funnily enough the spacebar. Bit of an awkward button to have to press excessively on most keyboards actually, so IMO this is a bad default for the main attack. Just a thought. As I'm not really a keyboard user for games like this I care about this rather a lot less though.) It would be less awkward if up was only a use and not a jump (but still could actually climb! You can't just bind up to the use action because you still have to climb!) and there was not a separate awkward button to actually use doorways and talk.

Regarding up to jump. Maybe they're basing it on the old Amiga/C64/Atari system where there was but one button?

Personally I have no beef with up being jump, might find it kinda awkward to press up to activate a chest or open a door. Entering a door however, that'd be just peachy-keen on up :-)

Now if we're talking the pick-up, maybe down instead of up? But again, It should be rebindable however you'd want it.

Also I second the need for an in-game way to unbind a button, I just went and double-bound the keys I wanted over the keys I wanted to use elsewhere. Not perfect, but at least I'm not out poking things with a text editor.

For what it's worth: I'm playing with keyboard and mouse. I'm having no problems jumping with space and didn't even notice that up/"W" were alternate keys for jumping.
The only keybinding that seemed strange was the map, which is bound by default to tab, I believe - instead of "M". (I wouldn't want to sausage-finger my way out of the map by accident if I'm Alt-tabbing out of the game. But maybe that's just me...)