Can I include a second default control option, say game can be played with 'mouse arrow up' or 'w'? Would be solely for the sake of convenience (1 hand or the other) and game wouldn't be designed to offer specific advantage to using them both. Or does it need to be a concrete choice? 

I don't think the idea of 'any and every key on ur keyboard can be active so long as it does the same function' is inline with the jam's purpose. But I think the idea of allowing 1 side of the keyboard or another has merit whether it for ppl with 1 arm or a broken arrow key or wahtever.